Why Is My Computer Running Slow

How long do you have to wait for it to completley load? Is there anything to do to speed up the process? Please help.

A while ago I swapped hard drives with a different computer and when I started my computer back up it took forever to boot and log on. After it does log on it’ll stay slow for about 4-5 minutes and I can’t run anything without my computer freezing but after that everything works fine. What can I do to fix this? I’m using windows xp, if that helps any.