With Win2k, I'm running one 2.7 gui and one 2.4 cli, which is much faster than 2 cli's. On my dual 550e's my wu times are 8-8.5 with the cli and 7.5-8 with the gui, with the occaisional long wu (13 hrs.) with the gui. When I ran 2 cli's side by side, the wu times were 9-9.5. I'm also running SetiQ and Seti Spy. I've got the clients in different directories, and seti q in yet another, with both clients patched to SetiQ.
Seems to be working so far, I get 5-7 wu's per day, depending on timing.
If you have any other questions about S@H on a dual, win2k, don't hesitate to ask. I'm glad to help the team.