My computer had 512mb of ram to begin with. Yesterday I put in another stick in(1GB)

I got the right kind of ram, It's compatable and everything. So at first my computer freezes every few hours. This morning it freezes.I swiched them around because someone told me that the bigger stick should be first. It worked for awhile online but it froze and again after at my desktop. I ran it in safe mod for abit so I could go online and find help. I went back to normal mode it worked for awhile but then froze again here at Darkdemon. Now I took out the 512mb one and am trying the 1gb one only. Nothing has happend so far. But I've only been on my computer for about 10 mins
What could the problem be?

EDIT: Nevermind, I think i fiqured it out