840m 4gb vs 820m

[OnlyAvailableUsername]

I can either buy a laptop with a 4gb 840m or a 2gb 820m but the latter is touchscreen and they are both full hd screens.I plan to build a computer in the next 6 months.Which laptop should i buy?

 

[13thmonkey]

2Gb the 840 doesn't really have enough power to use 4Gb