Alex I hope you don't find this condescending, but in troubleshooting, getting everything out of the middle helps. How difficult would it be to move it? If it is still slow, at least you get the patch cord, Ethernet run and switch out of the equation.
Absolutely true, and if this happened out of the blue to one machine I think I would try that. But I don't think it's a physical network issue since that would assume that both XP machines (each having identical issues) all of a sudden had something happen to their physical networking. I think it has more to do with how they are logically connecting to the server rather than anything physical. All machines in the office are connected directly to the same unmanaged gigabit switch, and it's possible both those machines' switch ports or cables went bad, but I would be surprised.
Have you tried installing a full AC on the computer with SQL and everything and run it to see what it does? Seems that would make it a network issue to a degree.
No, I haven't. I'm not really sure what I'd learn by doing that though?
Spend the money on a decent server, with a server operating system, and you wont have any issues. It doesnt hurt with AC to also have a Gigabit network and if you have clients that are wireless (upgrade to wireless-n).
Absolutely true. We're running a Xeon E5410 (that's a quad core) @ 2.3 GHz with 8GB memory and dual 1TB 7200RPM drives in RAID 1. So in terms of hardware we're sufficient for what we're doing. Why we're running Windows 7 Pro on it? I have no idea, I inherited it that way, and so far we haven't had the budget or any meaningful reason to upgrade to Windows SBS. We don't run a wireless network because we don't have the need for it and it's one more piece to secure. (Wireless router default security is still a joke without isolating the network and using a VPN tunnel, IMHO).
Thanks again for all the suggestions! You guys are all super helpful and I really appreciate it!