32 bit xp or is it 64 bit windows xp

i have trying to determine what windows xp bit version i am running 32 or 64. i have windows xp media professional roll up 2 but has updated too service pack 3. i think i saw an update with a 64 bit patch but i cant find that now.. how could i find out what i have any help would be appreciated....

The reason for wanting to know is ive read 64 bit version will recognize more ddr2 ram. 4gb max on 32 bit and it will recognize 4gb + on 64 bit versions. possibley like windows 7 64 bit. ofcourse it will still read 4gb but it will perform with the extra ram added. so with that being said how can i find which bit version i have...please help thanks.