i have question about the windows xp 32 bit and 64 bit wats the different between them  and which one is better and how can i know if am using 32 or 64 and is there any ways to convert  from 32 bit to 64 bit without formatting my pc

need to buy new windows cd?
or dl from microsoft (free)?

so what are the pros and cons of win xp 64bit?
and minimum requirement?

I fail your sentence as I'm a computer engineer

To run 64 bit OS, you need 64 bit processor and 64 bit motherboard
Core 2 Duo and above is 64bit. Duo Core is 32.

Maximum addressable memory in 32 bit BUS line is  2^32 = 4,29,4967,296 bit or 4Gb
Maximum addressable memory in 64 bit BUS line is  2^64 = 18446744073709551616 bit

Applications run faster NOT because of more RAM.. my gosh
On 32 bit OS, adding two 64-bit numbers requires 2 cycles
On 64 bit OS, adding two 64-bit numbers requires only 1 cycle

So theoretically, the instructions would run twice faster
You could do everything up to twice faster "theoretically"
The only disadvantage is driver support for old 32-bit hardware and 32-bit PCI cards.
But nowdays, more and more devices are 64-bit compliant

And by next year, everything will be 64bit
32-bit will extinct just like dinosaurs
Many people are already running 64-bit with no driver clashes.
Edit: For TS
Of course, XP and Vista both have 32-bit and 64-bit versions
We faced the same problem when we were using windows 95, didn't we?
Windows 95 had 16-bit and 32-bit versions. Later no more 16-bit..
32 bit runs up to to times faster than 16 bit
16-bit supports only up to 65536 bit of addressable memory

If your motherboard supports it, I can't see why not.

so u think there is no need to connect the 2gb 667 rit caz this ganna effect the 2 gb1066