This is the information for your specific Motherboard Chipset:
ftp://download.intel.com/design/chip...s/29056402.pdf
I suggest you go with an AGP card if the card supports the specifications listed on the link I provided. AGP is faster than PCI so it would be the better choice. But if you plan to go on PCI, you'll probably be assured more compatibility.
About 32 and 64MB, 64 will be better if you are going to be playing games but your system will not be able to handle complex games anyway because of your CPU bottleneck. But if you want the card just for surfing and doing your work, 32MB will be sufficient.!