it's not worth the time trying to figure that stuff out.. you never know what AMD or Intel are going to do with sockets.

939 looks to be a more stable upgrade path.. but it's almost never worth it to upgrade chips in the same board anyway.

Since it doesn't seem like you have a need for a specificaly fast CPU, I would just save your money and buy a reasonable box, with enough ram (1gb or so) than waste time/money worrying about upgrade path.

an Athlon XP 3000 is $110, and if you arn't going to run linux or the beta 64bit windows.. it's probably more than powerful enough for you. Why spend an extra $50 on socket 939 CPU, and possibly more on a motherboard for what ammounts to the same speed (Athlon 64 3000 $160 or so)

I feel it's just easier to hand-me-down hardware to other tasks than to try and upgrade stuff.. this way i maybe spend $500 on machine parts, and get something reasonable, but not super-great.. and then a year or two later, i can spend another $500 and get what might have cost me $1500 the first time around Then again, I do 90% of my work on my thinkpad (which i'm on now) so I don't buy much desktop hardware.