I'm a GeForce DDR owner. So far, the last Detonator set has been pretty good to me -- very stable, nice image quality, excellent speed. I haven't had any compatibility issues related to my GeForce (a lot related to my SB Live!, but that's another issue entirely ).
 
Overall nVidia has nice drivers. I've heard ATI's Radeon drivers are (for once) pretty decent, which is surprising considering how much flak ATI has gotten in the past for releasing *terrible* drivers for their new next-gen cards. So you might want to keep ATI in mind, but I think nVidia probably offers more bang for the buck.
 
Important System Info:
AMD Athlon Classic 750 @ 7.5 x 100
Abit KA7-100 motherboard
192 MB PC133 CAS2 RAM
CL Annihilator Pro OEM w/TV-Out
SB Live! 2.0
NetGear FA310TX NIC
Maxtor 30GB DMA66 7200RPM IDE
Mitsumi 4804TE CD-RW
Win2K SP1

Let me put it this way...I don't regret buying my WinFast 32Mb GeForce2 GTS.
 
In fact it has been the most trouble-free display adapter I've ever used. The nvidia Detonator 6.31 drivers are even WHQL certified, and work perfectly with DirectX 8 on my SMP Windows 2000 box.

My system is much like yours, and I own a DDR on 6.34. You have an intel/intel system, so the compatibility problems won't affect you as greatly an AMD/VIA (or maybe intel/VIA) system.
 
Go for it. You won't regret it.
 
------------------
NECESSARY EVIL
--Custom Built [H]ard PC--
<Windows 2000 Advanced Server SP1>
Intel Pentium III Coppermine(FCPGA 370) 800eb @ 954 (with an original ThermalTake Golden Orb heatsink)
Asus CUSL2 motherboard(no onboard sound)Rev 1.02 BIOS; rev 1003.004 (Beta)
256MB PC133 SDRAM (1x256 Mushkin Rev2 CAS 2:2:2 5t/7t)
SuperMicro 760A Full Tower(Modded for more fans and painted Rustoleum Hammered Black)
SP301-RA 300W Athlon Approved Redundant Cooling Power Supply
IBM15-7 15GB UDMA/100 7200RPM hdd & 30GB MAXTOR Diamand Max UDMA/66 7200 RPM hdd
7 80mm,3 92mm, and 2 120mm High Output fans(along with 2 80mm in Power Supply, CPU, and GeForce fans) spewing out well over 1000 CFM
Creative Labs SB Live! X-Gamer running on Liveware 3
Creative Labs Graphics Blaster Annhilator Pro GeForce256 DDR on Detonator 6.34
Logitech Itouch Pro Wireless Ergonomic Keyboard
Microsoft Intellimouse Explorer(Gen 1) & Everglide (HL Giganta)
Logitech Soundman G1 Powered Speakers & AIWA HPX222 Headphones
D-Link DFE-530TX+ 10/100 Ethernet Adapter
Compaq V720 17” (1280x1024) Monitor
Hewlett Packard 660Cse Printer
Memorex 4x2x24 CD-RW & Pioneer 6x DVD/ 32x CD-ROM
Hauppauge WinTV Go

I upgraded from a G400 to a Geforce 2 GTS 64m. Go for it. The Geforce is the best Windows 2000 video card out there. BUT play Diablo 2 in 2D. Performance in that game is still worse than my G400 using the 6.34 drivers.

I have thought a lot about the 3dfx vs nVidia war and have come up with this conclusion:
 
3dfx make absolutely excellent glide drivers and Glide is very nice indeed, with very few problems, BUT the sheer power and speed of nVidia make it top dog.
 
I upgraded from my Voodoo Banshee to a TNT2 M64 and haven't regretted it.
 
------------------
Life is a [censored]ually Transmitted disease with a 100% mortality rate.

Do you play a lot of games?
if so then nVidia is the way to go.
I never play games and I have found that nVidia tends to focus on 3d and not so much 2d. I just changed out my Gforce DDR for a Radeon two days ago. The Radeon kicks the Gforces but all around the room in 2d and in 3d I can't tell a difference. All of my work is in 2d so the Radeon is the one for me.

I am a gamer, that's why I want an Nvidia card.
 
The G400 is simply superb at 2D, but the 3D oomph it has is definately lacking in modern games.
 
If Matrox would announce the G800, then maybe I'd stay with a Matrox card, but there's no telling when they're likely to do that.
 
The GeForce2 Ultra card however, will kick booty all over Radeon in 3D performance (don't take that as an invite for a flame war) which is why I'm prepared to pay the big bucks for it.
 
According to SharkyExtreme, the GeForce2 Ultra managed the following scores in Q3A on max settings.
 
1024x768 = 111.8fps
1280x1024= 76.4fps
1600x1200= 52.7fps
 
The Radeon 32MB DDR got 67.5, 43.6 and 30.6 respectively.
 
In 3d Winbench 2000, the Ultra scored 120, whilst the Radeon managed 91.7.
 
As I said, I don't want to get into a war about this, but it's these numbers that are pushing towards the Nvidia card.

I've also got to add my bit! My brother has a geforce, and it's actually really good. I've got a radeon and although the 3D is silghtly poorer, and also alot of the geforce optimised demos from tranzmit.demozone.com don't work. However I've not had any problems with games, and I didn't even notice that there was a problem with Athlons and win2k. Apparently the performace was nearly half that of intel combinations and also win9x. But it was fixed very quickly. It's good to see ATI doing stuff quickly these days.
 
Anyway, the ATI has the major benifits of 3 textures per cycle (future proofing, good for bumpmapping, detail tectures etc) Excellant DVD playback and excellant Video in and out. 2D is 100% too.
 
 
------------------
System Spec:
Athlon 800
Gigabyte GA-7IXE F4
128Mb SSi PC100
Radeon 64Mb DDR (oem and proud of it)
Hauppauge Wintv Model 406
Realtek 8029 LAN (cnx to ISDN server)
Creative ES1371 PCI64v
Creative SBlive Value
Creative 48mx CDROM
Memorex TriMaxx200(DVD/CDR/CDRW/CD, 4,6,4,24)
Segate SS330630A 30Gb 7200 ATA4
LS120

Yeah, Geforce is definately the way to go. 3dfx's cards have not been able to keep up with the Geforce (especially in price ). Now the word is on the street that Nvidia might just buy up 3dfx because of the technology right suite that 3dfx just won. 3dfx's corporate value is mere peanuts compaired to Nvidia's. So pretty soon we may be down to 2 real 3d processor manufacturers, Nvidia and Ati, between which Nvidia is clearly the better.

Excellent. Thanks very much. Before I lay down the dosh, I just need someone to take my G400 MAX off of my hands.
 
Details are at:
http://www.ntcompatible.com/cgi-bin/ubbcgi/ubbcount.cgi?board=7&topic=000065&page=1