Windows 7 professional

[Rooky007]

I have windows 7 professional and got 4gb memory installed but it only seeing 3gb in windows is this normall?

Also is there a 32bit and a 64bit version and would getting a 64bit version see the memory?

 

[Rooky007]

I have a oem version so I need upgrade to a 64bit to get the 4gb to pick up as all it pick up at moment is 3gb when there is 4gb installed

 

[Rooky007]

Can I just install the new windows 7 on top what already installed will any software I alrwady have installed be ok or best do a clean install of everything?