Google Adwords can work SOMETIMES, depending on your competition. Here in Savannah, GA, USA, a quick search for computer repair leads to many many advertisers, making me think that the keyword bids would be pretty high.
Plus, for a computer repair business, using Adwords assumes you have a computer that is healthy enough to surf the internet. That cuts out a portion of your target audience right there.
I think you're on the right path, fusebox, as you have a good idea where you're going to advertise, now you have to figure how what you're going to advertise, or what your ads will look like.
Try thinking about common problems in today's computing.
- Spyware slowing down your computer?
- Want to upgrade your Windows Installation?
- etc
The beauty (and a pitfall) of marketing is that you can appear as professional as you want to. If you don't have the skills yourself, you can hire designers to create your website, business cards, logo, slogan, etc. for a reasonable fee. And there are plenty of them out there (me being one of them

shameless plug, sorry).
Big businesses use focus groups to determine how they advertise their products. You don't have to have 100s of people in yours, but you can guage friends, family, and coworkers as to the effectiveness of your rough draft material. Outside opinions always help... and if you subscribe to the "subjective reality" theory, then those outside opinions are really your own then, aren't they?
Bottom line: If you feel there is a need in your market for this type of business, then don't let fear stand in your way. It will drive you crazy!
-Jesse