Chances to generate bitcoins shouldn't depend on network connectivity above a certain base level. If you can receive blocks in a timely manner (somewhat low latency and a decently low packet loss), generating should only depend upon CPU speed (and maybe some other internal specs like memory speed).
Forwarding ports helps the network since more people can connect to you, but I'm running on a university network so I can't forward any ports and it works fine for me.
-connect is a command line option. Right click on your shortcut for Bitcoin, go to properties, and add "-connect 192.168.0.100" (no quotes, and replace the IP with the right one for you) to the end of the path.
Took me a while to figure this out, the command line is wrong (had to dig into the source for this)
It's
-connect=192.168.0.100
You forgot the equal sign

Otherwise, it doesn't work for either Windows or Linux
Damn, yeah I noticed that reading back through this topic. I get burned by that so often! Thanks, I'll edit my post.
Gotcha! Thanks knightmb and thufir for the info. I was mostly curious because of the exact situation knightmb mentioned - one can only forward a port at the router level to a single NAT'd host, so I wanted to see the best way to use all of my PCs and still manage to accumulate funds under a single "account". Based on thufir's confirmation, it looks like the best way to do so will be to routinely transfer funds from my "workhorse" PCs to my central PC that will house my "primary wallet," for lack of a better description.

Thanks again!
You can easily automate that task. I made a Python script to do just that. I'll upload the updated version to my site and post back here later tonight.