Technically, this:
PC Chips M861G v1.6a motherboard
Athlon 64 3400+ Venice
1GB DDR400 RAM
GeForce 6800 GT
Sound Blaster Audigy 2 ZS
This is a PC that I never really expected to have, and never really wanted.  When I realized I had enough junk lying about, I assembled it from otherwise unused and unwanted parts.  I found the case for free on craigslist.  I got the cheap piece-o-shiat SolidGear SDGR-600BX PSU for only $5 after rebate.  I got the 6800 GT for only $10 on eBay; it has a bad VGA port but the DVI is fine.
It currently runs WinXP SP3 with the 6800 GT, but that can easily be swapped out for a GF4 Ti4600 or FX5950 Ultra to get better Win9x compatibility.
When I originally put it together, I built a Win98SE image to go along with the WinXP SP3 image.  Neither image is dedicated to any particular video card.  My original idea was that I would use an FX 5950 Ultra and dual-boot using WinXP SP3 most of the time, and fall back to Win98SE for any incompatibilities; (European Air War, etc).  Instead, I find myself single-booting WinXP SP3 with the flawed 6800 GT 100% of the time.
Perhaps at some point I'll put the GF4 or FX card back into it and dual-boot the machine as I originally intended.  For now, I'm enjoying the 6800 GT under WinXP SP3 and hope to someday soon complete the original Halo game.  The 6800 GT is a really great card, but it's not my 1st, 2nd, or even 3rd choice for a Win9x system.