i bought a yakima system for my hch, as i do a fair amount of mtn biking. haven't yet had a chance to try it out, though, as most of the trails around here are socked in with snow. on yakima's site they have a fit guide, which will tell you exactly what you need to get a complete (or partial) system for your car, how to mount it and how much it wold hold, etc. i image thule has a similar thing.

the thing i like about a system like yakima's is it's easy to customize, and if i get a different car, all i'll need is a different set of clips--a total cost of what, 60 bucks--in order to make it fit.

good luck!