IMO the best bang-for-the-buck improvement is to go with an SSD. More so on a laptop because the 2-1/2" drives are dog slow. If the machine is running XP or Vista, stick with Intel because of their trim utility. If laptop, go with a 240 gB 535 series for lower power consumption, $115 at Newegg. For desktop get the 240 gB 730 series for more performance at $140. If running win 7 or higher, the trim utility isn't needed making Samsung SSD a good alternative. Lower cost specials are frequent if you're not in a hurry. Intel and most other SSD makers have a "migration" utility available to clone the disk. Just make sure the current disc is SATA. If the machine supports PATA IDE only, get a new one! Increase the RAM to 4 gB, should be doable for $50 or less. Should run a lot snappier for less that $200. Alternatively, there are some reasonably fast laptops for $400 or less new. Dell Inspiron with new generation i3 CPU is an example. I'd just plan on using a full size USB keyboard with it.
