I'd say to stay away from the HP. I had one and know a few people who have had one and parts just keep crapping out in it. In mine, the fan crapped out and blew the CPU.
As for gaming, it doesn't really look like you'll be doing any of that with those computers (unless you're a big fan of Nethack). You're probably going to want something with at least 2.0GHz of processing power, but more would be better. Also, look for something without integrated graphics as they tend to be worse than what could be installed.
Also, if you're looking at using Vista for any long period of time, 2GB of RAM will only just barely cut it. More will be better, but if you upgrade to 7 then you should be alright with 2GB.
Best of luck!