What should I do before installing AV software?

[golgi]

I read somewhere here that it's a good idea to do a few things before installing anti-virus software. Some of the suggestions listed were: run defrag, clean up hard drive, fix registry. I know how to run defrag, but how do I "fix" my registry? If anyone has any other suggestions (or links) I'd appreciate hearing them.

The AV software that I'm planning to get is Norton Antivirus 2001. (I'm running Windows 98.) If any of you have any opinions or suggestions about this choice, I'd appreciate those too.

Thanks!