I'm cracking RC5 on seven of my own comps. OS's include Win95, Win98SE, and NT4. Never had 
any problems from the client or the hardware even though three machines are dualie Celery 300a@450! One is a cheapie PCChips mobo under a K6-2 300, still no trouble at all. I even let it run while in Falcon4 and UT. Been crack'n for 580 days 24/7 with no letup in sight (until 
I find the key anyway 

).
The only downside to all this is that I've become an incurable statsaholic like many others **cough
russ cough** on the team.
When you join be sure to let us know over at the 
Distributed Computing forum so that we can give you our "welcome aboard". Unfortunately we reserve the Hot tub, Babes and Beer perk until you hit a million blocks. Hehhe, looks like 
I'm next in the list!!! Woooo-o-oMoooo-o-o-o-o!!!.
But seriously folks, come on over and check it out. We can use your help and we promise it won't hurt, HONEST!!
Geoff