Computerilitate, you can do several:
1. Defrag your computer (as suggested by Ixion) which is actually grouping the data clusters together, that belong to the same programs.
2. Take off the programs that are fired during start-up (look at the icons that are on your lower righthandside screen, if you have many, consider to deactivate some).
3. Programs like CleanSweep, etc, will go through the files in your computer and delete redundant files, clean up the Windows Registry file, etc.
Other than that, if you are using PacNet, I agree with PaulN - It's horrendous. I have switched to StarHub's free internet. It's much better! I use PacNet as an email address only now.
Hope that helps ...