32 - 64 bit?

So i only just noticed that my system is not using the 4GB i have in my computer, only 3.something, after a bit of google searching i found this is because im using 32bit OS.

I am considering changing to the 64 bit OS but i have a few questions.

I downloaded both the 32 and 64 when i paid for my upgrade copy as both options were available to me so i thought 'why not'. Can i use the 64 bit now that i have activated my license or am i now only allowed to use 32?

Since my copy was upgrade, will it work for a fresh install (in either 32 or 64)?

Also, Ive never really understood the difference between 32 and 64 bit, can anyone tell me of any problems im likely to encounter if i switch from 32 to 64?

Finally, in case its important, if its all possible i will be doing the switch with my incoming upgrades, CPU will be i5 750 not my current one.

X64 requires a compatible CPU. The e7400 is compatible.

Information about some of the ways to use an upgrade version of Win7:

Clean install with Windows 7 upgrade media? Get the facts! | Ed Bott’s Microsoft Report | ZDNet.com

Activation of a new install of the X64 version is basically the same as for a re-install of the 32 bit version on changed hardware. (At worst, you'd have to activate by phone.) The basic principle is: one license, one PC. X86 (32 bit) or X64, doesn't matter. I haven't tried a 32 bit key on the 64 bit installer or vice-versa, but all that I've read indicates that there will be no problem.

The main concerns with the X64 version are:

16 bit software cannot install or run. (Some old 32 bit software uses 16 bit code in its installer, so that can be a problem.)

X64 won't permit unsigned drivers to be installed. (That's not the same as non-WHQL drivers. I install them frequently.)

Some hardware has no X64 drivers. You may wish to check what's available for your peripherals (scanners, sound cards, etc.).

I'm not sure that I'd recommmend going to X64 for 4GB of RAM. It'd be satisfying to access all of it, but the practical advantage would be slight. It'd be justified if you have more than 4GB, and if you have any 64 bit applications. (There aren't many. I use Photoshop CS4, which has both 32 and 64 bit versions. 32 bit applications generally can't access more than 2GB of RAM, or 3GB if they are aware of a switch that can be set in Windows X86.)

thanks for your reply. i think i will stick with the 32 bit

i think i will stick with the 32 bit

A wise decision. I have both and I hate the 64bit (it came with the laptop). A lot of stuff does not work on it.