I'll be working during the summer and will need a laptop during the hours that I work (I will lifeguard, so I will have times of nothing to do)

What I need in it is:
-long battery life (6-8 hours or more???)
-light/small (15"?)
-built-in wireless

that's pretty much it since I will only be doing some minor compiling and maybe text processing email stuff.

Also, looking for as cheap as possible (500USD or less possible?), please recommend families of laptops, company, whatever.