I did the power locks from a kit very similar to below:
4 Door Power Central Lock Kit w 2 Keyless Entry Car Remote Control Conversion | eBay
Just follow some tips in this thread:
http://www.aveoforum.com/forum/f84/a...48/index3.html
Pretty simple DIY project, especially if you have any sort of experience with basic stereo/speaker wiring. Very similar, you're popping panels off and identifying and running wiring.
The only pain in the azz is the front 'molex' connectors for the front doors. Pretty sure there is a link in the thread above, if not, just google molex. Also, plan to purchase some extra wiring if you don't already have any. Plus soldering gun, heat shrink/electrical tape, etc.
I can't comment on the windows, because I can live with manual windows. But keyless entry has always been a must have for me.