Alex, 640MB of ram, well, FORGET IT. You could try to capture it in sections less than your drop out, but I would hate to see what you render time is going to be on your end product (it will likely be measured in DAYS, not hours).
Spew $500 and get a reasonable machine... these are NOT the best video machines, but they will get you closer to "reasonable":
http://www1.us.dell.com/content/prod...=19&l=en&s=dhs
Make sure you have an ass load of ram (my editing machine has 4 gigs, and the extra rendering units for after effects all have at least 1 gig).
Alex