Depends ricelover. FreeBSD would be fine as long as you don't try to build anything from the ports. Stick with packages instead. I was going to post a link to FreeBSD 4-series, but looks like it's gone. That should work great in your laptop. The 5 or 6 version could be a bit heavy for your laptop though (wild guess).
In this case, go with Dragonfly BSD. Not only the name is cool (lol), but it is basically a fork for BSD 4.x, which in my opinion, was awesome.
Remember that you will find a lot of differences between Linux and BSD. If you never tried BSD before, don't be afraid, the documentation is great