Are there any 3rd party programs that would allow me to customize the rights of certain computer users? For example, one admin may not be able to look through other people's files, but a limited user may be able to look through any files, a certain user cannot access certain drives or paths, a certain user may be able to download things or access programs, etc.? Windows features barely have anything. It's either you are an admin and have access to everything, or you're a limited user. That's why I was wondering if there are any programs out there that can customize different things.

Does anybody know if xp, vista, or windows 7 may have any of this? I know that vista isn't that great but most computers come bundled with it these days and I don't want to go through the of hassle of buying new software or OS'.

Which version of windows are you using?

Disabling simple file sharing might be your answer, i'm not sure if you can do it on XP home though.

Depending on the version, you can check out secpol.msc to see if it provides the security granularity you need. (Use start/run to run it)
Xp home doesn't have it. There are other option for home though.

I have vista home premium and xp. I want to have more options though.