It's a tough call when your computer is still fast and powerful enough to do a lot of the things you want, but falls short in a couple of places that you want to upgrade. Sometimes it can feel like your best bet is to just build a new computer entirely (especially since it doesn't take a lot of money), but at the same time, you could just upgrade the thing that's causing you problems and call it a day. The lines are blurrier than you'd think. Here are some things to considered; will the old machine support the todays windows programs and other Microsoft programs. Can you find parts for the old machine, depending on the hardware interface, some the new hardware will not work on the old machines, and finally, does the manufactures still make and offer supporting drivers for the phased out machines.