Mounting ramsinks on video cards isn't that hard. Most problems stem from not cleaning the ram. The thermal pads leave a film of silicon oil that won't come off with alcohol. You need goof off or my fav Artic Cleaner, a two bottle set. Sold at many PC online and earthbound stores like Frys.
I use Seksui (I think) thermal double sided sticky tape. Very very thin and one of the very best out there. It has never caused me any problems.
http://www.xtremesystems.org/forums/archive/index.php/t-109836.html
http://www.ocforums.com/showthread.php?t=544844