Upgrading from 32bit to 64 bit

[Blorp Kola]

I am looking to upgrade my current 4GB of ram to 8GB. For this I understand that I need the 64 bit version of Windows XP. I have a hard drive with 3 partitions and I was wondering whether it was possible to back up all of my stuff on another partition rather than using an external hard drive. Does installing a new OS only format one partition?
Thanks in advance for any help.

 

[Emerald]

the short answer is Yes

however, after backing up your data you might just be able to upgrade to the 64-bit version without reformatting.