I remember when the D3 alpha got leaked, my friend and i ran around frantically on the net trying to find it (iRC, newsgroups, secret forums, direct connect, etc..) and for about 2 days came up with nothing, until we FINALLY got ahold of a copy...
we burned that thing like nobody's business and were running it the next evening on our respective machines.
[too bad its all over kazaa now, that makes it too easy... cheaters!]
it actually sometimes runs pretty decent on my machine.
i have an XP 1800+ @ 217*8.5 for like 1840mhz
512MB Corsair pc3200 @434mhz, 6-3-3-cas2
Leadtek GF4 Ti4200@ 320/590
not bad, not bad at all. frame rate cuts off completely pretty often though when many baddies get up in your face, heheh...
after seeing the NEW E3 video, I reinstalled the alpha again (its a hefty 1+ GB for a 3-level alpha) to have some pre-release joy...
meh, ive run it at a better rate... im having this problem lately where the system locks up every minute or so, then comes back about 10 seconds later. Happens in every game I run now

not sure what the issue is, but i just switched Nvidia drivers so maybe itll help?