My system is a windows 7 with 6gb ram, but the exe loads max 495mb.
I don't know if it scales up with the operating system or the resources, but i'd have no problem to have a 2gb exe 
I rarely load up all the 1gb version, but everytime i open some new behaviour i think about the memory.
Can you save your games and re-download nightly (window installer) from here. We've fixed the whole issue up this past week. You should be getting more than 495M.
http://community.stencyl.com/index.php/topic,3874.0.htmlThese are numbers I just got after downloading nightly.
Personally, I've win-xp with 1G ram. So not as much as yours. But I was still able to get above that number.
This is my test.
Using window task manager, my free memory showed about 730G before I invoked stencyl.
I think the magic formula is always
0.966 (there is this extra scaling) X 80% X 730G (free ram) ~= 568G
Next, after launching stencyl which already has resource monitor from Forge extension, I got:
33M/140M (563M) showing in resource monitor. The last number here is the max memory allocated.
^^^
So, you can see the two numbers (563 vs. 568M) are very close and way above 495M.
Please make sure you are using the correct launcher (the red Stencyl C iocn under Program Files)and also not capping the ram somewhere.