I use WinRAR to open .rar and .zip files. Love it!
It's not free, but has trial version for try-out.
I also use winzip and have no problem opening .rar files or any .zip file. Try it, you'll like it.
You have been given excellent info. I use it and it is great ! I use Windows 7 on 64 bit and have other digitising programmes and it has not caused any computer problems.
I downloaded Winzip7 a couple of weeks ago and have very successfully opened .RAR files