Invoice or customer management software?

Me and my friend are having a go at doing our own computer repair business (worked for the Man for years), and we’re trying to find a good way to manage invoices/customers. Really wanna do some thing web based, PHP/sql would be the bees knees, but any thing is better then writing it all from scratch (maybe).

Any one have any experience with this kinda thing? We used to use MS pos software, which was sql backed. While that software sucked, some thing along those lines would be fancy.

Found this for any one looking.

Thats a self-hosted option. There are lots of hosted options out there. looks pretty nice, for about $20 a month.