It looks like you are using a Prescott processor from what I can see right off ther bat. The 3GHz version P4?
For the motherboard, you can use any type that supports the LGA775 socket and Prescott CPUs such as the one below:
ABIT AG8 Socket T (LGA 775) Intel 915P ATX Intel Motherboard
This board utilizes PCI-express so its much better. What's the price range you are willing to spend? It will fit in pretty much any mid tower case that supports ATX form factor, for example this one:
ASPIRE X-Gear ATXB5KLW-BK Black Steel ATX Mid Tower Computer Case 420W Power Supply