I have a laptop with only a 6 GB hard drive, which is networked wirelessly to my main PC. I am wondering if it is possible to install games directly to a shared drive (which resides on the main PC) from the laptop, so I can play the games from the laptop without using its HD space. Anyone?

I don't think this would work unfortunately. I'm pretty sure that a game can only be played from a machine where that game is installed on a local disk. As soon as the game is installed remotely, the throughput of data would just be way too slow, even on a 100mbps network, let alone a wireless 11/22mbps setup.

I do have a wireless-g network, but I don't know if that would make it much better? Do you think thruput is the only factor, or would the game not install correctly that way?

You should be able to install across the network but I'm pretty sure you wouldn't be able to actually run the game. The more I think about it, I don't think throughput is the issue - I think most software is simply coded to run from a local disk, not a network location. In other words even if you had a gigabit connection it wouldn't work. There's no harm in trying though. Give it a go, I'd be interested to hear if it did work!