I have a Hypersonic-PC GX6 Sonic Aviator that I'm very happy with. It has a P4 3.06Ghz processor in it and can be configured with wireless - I just got a wireless router though so just put in the adapter, which is no big deal. It can run basically anything (though it gets hot) with the Mobility Radeon 9000 in it. Plus it has a very cool metallic red paint job
All told it was over your $2500 limit, though I did get some extras like XP Pro and Office installed. You can check their site, though, http://www.hypersonic-pc.com
. They might be offering different customizations now. Be forewarned, though, it is big and heavy and sucks the battery dry pretty quick!