[ErroraBorealis]

This is more for people who fix computers to make others happy or for money...almost a SEing technique.
1. Turn up the mouse sensitivity if possible. It makes a difference.
2. Clean up the desktop a little bit, on older PCs it makes a difference and it looks better. You may want to ask about this beforehand.
3. Defrag. Obvious one.
4. Disk cleanup. Deletes a lot of temporary stuff.
5. Remove startup programs using MSCONFIG. Also may make startup less aggrovating.
6. Check and scan for viruses. They use up extra RAM and cpu.
7. Run a registry cleaner, just make sure you don't find one that acts like an infection and wants you to pay. I've heard CCleaner or whatever it is is good.