Look Dude Windows XP Service Pack 2 supports 32bit/64bit OS's but Windows XP Service Pack 3 supports only 32bit functions so you need to upgrade to Windows Vista or Windows 7 for 64Bit Operating Functions! Plus with all the hacking going on in various countries vs Windows XP from July 2nd-July10th, Microsoft Decided to stop supporting SP2 with 64Bit Extensions. Only Supporting Windows XP 32bit with service pack 3 until 2014!
No this is wrong. As ijack and zoron said, XP 64 is based on the server 2003 kernel. The code base is different and so are the service packs. X64 RTM had all of XP 32 SP2 functions. Its not like Vista/7 where the 32 and 64 bit ran in parallel. XP 64 will be supported until 2014.