Can I upgrade this computer as a project?

From the looks of the hard drive info, it has a Western Digital drive in it now. Newegg has a Seagate and a WD in the size you request. They are ATA 100. Both are recertified.. Crucial would be the place to go for memory, take your information on the computer with you when you visit. Your computer takes DDR PC2100 memory. This is a Compaq computer, parent company HP. It is listed in their site. There were 4 models of the D510. The CMT is listed. Most were Intel P-4 processor equipped. A Intel 845 chipset. This may be a problem with Windows 7. I have a older Dell 4600 which contains a Intel 865 chipset. Windows 7 is not supported here. Intel has not and never will supply the drivers for it. You may be able to do a upgrade to Win 7 from XP. It is a little bit of a different flavor. Links are below. Hope it helps.