We'll its dificult to say what the minimum requirements will be, but we can assume or make a good guess based on the Q3 Engine. Also, if you have plans to upgrade, primarily for JK2, wait! You are going to pay 30%-50% more now, then if you wait until like January or February of next year. Although, you could upgrade to a 1 gig P11 with 128mb of additional ram, with a 370 socketed mohter board, for $300( assuming you knonw how to install it). As far a video card goes , this best card for under $200( right now anyway)Asus-7700 Delux 32mb Geforce2 AGP W/DDR,or GeForce2 GTS 64mb with DDR( my card).
Also, with video cards. Don't always assume that the bigger the card, the better. There are several cards on the market that are 32mb in size, but can easily out-perform a differnt chip that is 64mb in size. As of now, my reccomendation is you are safe with any card powered by nVidia technology, GeForce series and invest in DDR technology.
As for good deals on hardware) aside from the occasional steal on ebay, which is good place to check) I use this site allot: http://www.mwave.com
I hope this helps you out Yoda, and I will see you on the zone( aka-headchange)