To 64 bit or not to 64 bit

[Chaky]

Here it goes:
I've built a machine that is 64 bit supported. (Athlon 64, all drivers and so)
I'm using XP (32bit)
My HD is configured with 2 partitions. (3 if you count the 8 MB one)
I have recently obtained Windows XP Pro 64bit.

My question is: Will I gain any (gaming) performance increase by installing 64 bit OS?

Bare in mind that this machine is used for gaming only.

Cons I've learned so far are:
- lack of support for 16 bit applications (old games)
- questionable compatibility for 32 bit applications (new games)
- xp Pro 64 bit is based on windows 2003 server, which is more than needed for my machine (simpler OS - less strain on system)

Pros:
Acctually, there is only one reason I'm even thinking about 64 and the reason is some test I ran on my system. The test was to determine how well will battlefield 2 run on this system and results were great. Only negative result was the OS not being 64 bit.
I'm reluctant to install new os 'cos I'm not sure will those 2 come in conflict with each other. I imagine that both systems will try to use same system folders ("Program files", "Documents and settings") thus renderind 32 bit XP corrupted upon 64 bit OS installation (i.e. overwritting registry files at "documents and settings/user", "Program files/common files" etc.).

Somebody else's expiriance at this field is welcome.

[caperjack]

if you have second partition with enough space to install 64bit winxp ,then do it ,it will not interfear or use same system files as the 32 bit os .

[Chaky]

I've compared NTLDR from my root and one on winxp64 CD and they are NOT same. I wonder if I will be able to multi boot to 32 bit xp or will I be uble to remove (if not satisfied) 64 bit windows. Something's tellin' me NO.

[caperjack]

Ive never done this ,but just giving the was multi boot work i don't see what difference it would make .and yes if you have your hard drive partitioned you would just have to format the partition with 64 bit on it ,unless you have something different than im use to doing when i partition a hdd.