ive just finished downloading the 32bit version of Windows Vista RC1 from the official Microsoft link, the download went fine but when i opened the Winrar archive all that was in it was a small text file saying "This disc contains a "UDF" file system and requires an operating system that supports the ISO-13346 "UDF" file system specification." But no apparent sign of the iso file, even though the archive is 1.99Gb in size. whats going on, where is my iso.

The file you download IS the ISO - you need to open that file with Nero, or an appropriate burning program. You should find after that it'd be ok...

Marc