The most important thing is to make sure it will work for you.  Check all of your drivers (video/mb/audio etc) and make 100% sure they all have 64bit driver support.  While they should, it does not mean that they do.

Also, 32bit will always run faster with under 4gb of ram simply due to addressing (the amount of speed increase is almost 0, but it is still faster).  Going higher does not matter since you have to have the 64bit environment to run.  As far as gaming goes, I load everything I play directly into RAM (running 8gb atm) so loads and whatnot are faster.  Since 64bit win7 has b/c with 32bit applications and one day they will make apps purely in 64bit, Id suggest going with 64bit.

There are only 2 reasons to get the 32-bit version

1) you have a 32-bit processor
2) you have legacy software/hardware that doesn't work properly on Windows 64-bit platforms

Both are incredibly rare for a casual user. A casual user would be someone who uses Windows Office, Photoshop (or Gimp) watches DVDs, plays music, uses the internet, and plays games, but doesn't hold onto 20 year old software.

Point 2 may be a factor if you are a programmer or designer of some kind, as you aren't using mainstream software that may not have been updated yet. Point 2 also is a big factor for large corporations that live on legacy software (ever go to the hospital and wonder why they are still running DOS programs )

EDIT: forgot legacy hardware, obviously check your the companies drivers page for 64-bit versions. Probably not a problem though unless the hardware is really old.

I'm not sure about their licensing, but if you do eventually upgrade your PC that contains more ram then you don't have to re-buy a 64 bit version of Windows 7....of you go for the 64 bit version.

64 bit, without question. Newer CPUs will respond better to the 64 bit version, I thought I heard that 32 bit versions of windows wont take advantage of multi-core cpus?

I just made this decision a few weeks ago.

I'm now running Windows 7 64-bit.

After reading tons of articles, checking compatibility lists, and generally doing a ton of research... I came to the conclusion that there was no point to getting Win7x32 and it's a decision that I'm very happy with.

Checked all the components in my computer everything runs with 64 bit so I guess I might as well go with 64 bit now just to future proof my computer for a while. Thanks for the advice guys :)

The bolded is completely false.

i would go for 64 bit for sure, cause of the support of more RAM.

Edit: Seemed I was wrong after doing some research.

No, it is 4 GB - but that also includes things such as VRAM, among other things. So if you had a 1 GB video card, you'd be limited to 3 GB memory on a 32-bit system, or less.

No, the 32 bit os can see 4GB of RAM, but that is Video RAM and System RAM.

EDIT: jefforange beat me to the punch