Dell XPS M1530 - Windows 7 64 bit memory?

I have a Dell XPS with Windows 7 Professional 32 bit already installed. I also have 4 GB of RAM. I just found out my laptop is able to run Windows 7 64 bit and I am able to get Win 7 X64 through a system run by my college and Microsoft. I would like to add two sticks of 4 GB RAM to my XPS but I am confused as to much RAM my laptop can support. I have read that Win 7 X64 can support 8 GB of RAM (and much more) but I have also read that the XPS M1530 can only support up to 4 GB of RAM due to hardware constraints. Can someone please clarify this?