It looks like my older brother is about to change jobs - from lawyer to shooting range proprietor - and since I'm the family 'computer guy' I have the task of coming up with and setting up the in-store equipment.

Only problem, I don't know how to start or where to look. I'm a web programmer, not an IT specialist.

To that end, I figured I should ask the pros.

Users: 3 (myself, my brother, and his business partner)
Equipment: 1 Windows (likely 7) desktop for POS software, 1 Windows desktop/laptop for backroom use (bookkeeping, etc.)
Other: ??

I'm looking for a reliable and, well, idiot-proof way to handle backups. Neither my brother nor his business partner are tech savvy (A web browser, email, MS Word and Excel are about the extent of their knowledge), so I need something they can handle. On-site would be preferable to off-site, given my brother's hesitance to have sensitive business data be handled by an outside source.

I'm also looking for a small on-site server. I estimate that, at most, only 2-3 users will need access. A linux solution would keep costs down, but I'm concerned about Windows <-> linux interoperability.

Would the store security cameras' storage be handled by the security company, or would we have to stream that data to our own server? I know from my own experience with personal security that the company gives/loans a recording device to the home owner, but I'm not sure about business security.

I know this sounds like a shopping list, and it's pretty vague. I wish I could give more detail, but between my own ignorance and things not being 100% nailed down on the business end, I'm a bit stuck. At the very least I'd like a nudge - links on a place to start, what to look for, things I need to think about, etc. - for this endeavor.

Thanks.