On one of my trading PCs, I have 5monitors hooked up.(1 agp-dual, 1 PCI-E dual, 1 PCI) nothing but trading......no updates. the other PC has all the junks and 2 monitors. haven't had a problem.
XP is already/still working perfectly. No reason to go through the hassle of changing. (I have W7 on a couple of other machines, but my trading stuff is still on XP. Besides, I don't see many/any benefit to running W7. It's said to be "more secure", but I don't have security issues with XP.)