Yeah but how the hell are you supposed to download the patch if you haven't even got the game running? Nice solution...
True enough, if there's one thing that sucks about Blizzard is customer support... :-\
Anyway, I would ask my firend to bring his comp to my house and change each part, one by one... The graphic card, the soundcard, the memory, everything... This may reveal what part causes the problem. Start with the memory.
Don't throw away everyting if your comp work fine otherwise...
My system has nothing special, an ASUS a7v8x motherboard, a Radeon 9200 128MB graphic card, 512 MB memory (Samsung) and an integrated souncard, that's all... Memory needs to be doubled so that I can set the graphics settings to a better quality but otherwise it works fine.