windows advisor is right ,you have a 64bit processor and it will then also use all of your 4gb of ram too . while your machine is not state of the art for these days ,it will run windows 7 reasonably well ,its not such a resource hog as Vista before it . your only possible stumbling block will be the graphic card , if you update to windows 7 ,that supports the latest DX11 your old card will almost certainly not .and if its an onboard card (built in) your stuck . run belarc advisor (its free) google it and download it ,it will tell you what you have installed ,and give some advice tips too .
Acer Predator 21X review