"Would my system be 32 bit? "
You'd almost certainly know already if it was 64 bit, but you can check:
Right-click My Computer and choose Properties. If it doesn't mention 64 bit, then it's 32 bit.
If you fit 4 GB in a 32 bit system, it will work fine, but Windows can address only 3 GB. As memory is so cheap, it hardly matters.