First thing is to see if the motherboard has an extra IDE channel to add another hard drive. If you only have PATA (IDE) available, then usually there are two channels but check to see. Some boards may have both IDE and SATA. If there is a SATA connector then that is a choice, too. While you are looking, check to see if there is another connector on the power supply for an additional drive. SATA drives use a different power connector than IDE but there is a converter available for that.
I'm sure this has been asked before, but I couldn't find the right answer by searching.I have a Dell Dimension 8250, Windows XP Home SP3. I'd like to add a second, larger hard drive. The one that's in there is a 120 Gig ultra ATA 100, 7200 RPM with IDE ribbon cable. I'd like to put in a 500 Gig hard drive. Do I have to search for a particular one to match what I have? I just recently added memory to the computer and I had to find the exact product to match what was in there (Rambus Ram). Does adding a hard drive work that way or can you put any kind in?