Laptop Problem

Can someone please help me. I have just bought a new laptop. So I turned it on, charged it all and everyuthing and just opened some of the programs to check em out. But very often it freezes. I mean, i could be in the middle of writing a paragraph in Word and then it would just freeze like that. I have so many times been forced to switch it of using the power button and it keeps hapenning. It has also freezed when i inserted a cd but not ran it, and using other sofwtare installed on it....

I have downloaded windows update but it still continues. The only thing I have done major to it is that when i was at the shop to get it, i bought a Kingston laptop 258mb ram and the guy helped install it for me to make it 512 RAM. The computer recognises it (well it says 512 in system info) so does this mean that it is ok and that the extra RAM is not conflicting with the original one?

Basically, can anyone tell me what are the possible causes of freezing, and how do i know that this extra ram isnt the cause of the freezing. I mean, it is brand new. Can RAM conflict with each other even tho the system info (and norton system works) says there is 512mb?

Specs: windows xp professional SP1, pentium M, centrino

Please help, it is my first ever laptop and am dissapointed with it.
Thanks

Laptop Problem - Help!