I've had America's Army for a fair while - very good.
Joint Operations looks pretty cool (love the sniper 'gillie' suit - great stuff)
Downloaded the demo...it was unplayable on my pc.
(P3 933, Geforce 2 GTS, 384mb ram)
I'll probably wait till the end of the year before upgrading.
p.s
I have a flight sim called 'Lomac' - Haven't played since it came out since my pc is so slow.
I want to hold out as long as I can so I can turn all the options up to their max with ease. (From what I hear, the special effects over the ocean/water have to be turned down even on a P4 3.2 - I might wait till P4 4.0 comes out...)