rar files on tomtom maps

[andromeda1]

have downloaded latest uk maps(version 6.75) as rar files, but when trying to open them my PC says it doesnt know what system was used to compress them. What program can i select from the list (ie notepad, word, etc) to do this for me, and has anyone else found the same problem?
I can download and open speed camera files with no problem, it opens them automatically
HELP please

[hda5]

You need to download a program called Winrar to decompress and extract the files/folders inside the .rar file

You can get Winrar here
http://www.rarlab.com/download.htm