I've not tried Diskeeper 7, but the last version I did try I wasn't impressed with. As far as I could tell, it needed enough free disk space of the largest file on that disk, to defrag it... which I found quite pathetic, especially when Speed Disk works no matter what.
 
As I've used Norton's products since the beginning too (since waaaay back in the DOS days when PC Tools rivaled them), I doubt I'll ever switch.
 
Oh I also tried O&O Defrag once, but I found that gave me some corruption once.

I guess I am on the other hand, as I have found most of the Symantec line to be evil incarnate . I do like the Diskeeper line (from 4.x), but I have been looking to try out Raxco. Symantec does offer the ability to defrag partitions that are formatted beyond 4KB in cluster size, but that's because they have written their own APIs to accomplish this (which I have never been a fan of). I think that both are good products though, and that you would do well with either (or even Raxco and O&O).

I've been a user of Norton for ever and a day and don't have too many complaints. Never tried disk keeper though.

What about the windows built in defrag program??

Well windows 2k and XP built-in defrag tool is a light version of diskeeper, with limited functionality(no boot time defrag, no scheduling, no MFT defrag).It's even recommended by MS to buy another defrag tool for this kind of operations.