I have a very old HP Compaq d530 CMT that I put Ubuntu on, but there is something screwed up. I only see a desktop pic and nothing else, but I already got help for that here. The Dash and launcher is still missing, so I think that I need drivers for this old PC, but I don't know what to get and I don't know what brand the GPU is, but is is onboard graphics. The motherboard is 323091-001
You will have no problem when you install Xubuntu:
Unity runs quite bad on old computers as it more resource hungry, I recommend you to install the Xubuntu version and start having no problems at all and notice a big speedup improvement.
PS: Use the 32 bit 13.10 version as you have less than 4 gigs of ram and you aren´t using a latest-gen processor.
PS 2: Try to update the BIOS of the motherboard.