I currently work for GS and I've been working for GS since Best Buy launched it in all its stores and let me tell you something.. it's the worse job you can ever have if you want to work on computers. All you do all day is ring up computers, sell GS services, sell more GS services, oh and did I mention you sell GS services? Anyway, so if you're not helping a customer, or selling GS services, you're actually working on computers and what you mainly do is spyware/virus removals, memory/video/etc upgrades, os restores and data backups. In an average 8 hour workday, you spend about 1-2 hours working on computers, 3 hours if you're lucky and customers aren't asking you where the bathroom is.
Out of the 2.5 years I've been working with BBY, the most challenging thing I've done is install drivers for a hard drive so it can see past 137 gigs.. I got happy once when I got to install a motherboard... but that has only happend ONCE in 2.5 years.
Long story short, if you want to do computer repairs, like.. really work on computers, go to a small computer shop or become a Double Agent for GS (they're the ones out on the field fixing computers all day). But again, you'll be expected to sell and the most challening thing you'll probably do out on the field is virus/spyware removals. GS has made me never want to touch a computer again while I'm at work because I have a fear of not being able to complete the computer because a customer pulls me away from it.