Yes to your original question, but why would you upgrade the motherboard now and not the cpu?
The mobo upgrade by itself will not give you a lot of extra performance, and the KT400 is not top of the line for socket A. Best to hold off until you can get a CPU and Mobo and upgrade together IMO. If you are only talking about a few days or weeks, then fine, but you should still consider going for Nforce2, as it is really about as good as socket A will ever get.