GTS 250 512mb or 1G

Hi , im a new pc gamer .Just starting to build my own PC , and was wondering for my current 19" Samsung monitor..

Will the Gts 250 512MB suffice ?

Also , if some day i buy a bigger monitor , up to what size could i get and still get my gts 250 512mb to work just fine ?

It isn't the size that matters(well,in some case yes:P) but the resolution. If you plan to go over 1680x1050,get the 1gb,otherwise the 512mb will be enought.MonsieurX

Do you think i could settle for a 9800 gt 1GB ?

or is it to much of a downfall .(price needs to stay around the same )