I'm an Intel guy heheh but I seem to remember reading somewhere about a motherboard has to be compatible with a barton core CPU
No the core has nothing to do with compatibility. It matters on some of the 64's, the winchester core because it uses .09u technology and it requires a BIOS flash for some boards to recognize it but other than that, if it says up to XP 2600+ then they are fine.
yes that is it. so after installing it... what do i have to do to let the comp know that this is a new cpu. ?
You don't do anything.
Clear the CMOS (read the manual to locate the CMOS jumper pins, generally near the battery) move it from pins 1-2 to 2-3 for about 5 mins and it'll clear it, make sure of course your PSU is turned off and preferably unplugged so absolutely no power is going to the board.
Then move it back to pins 1-2
You might have to go into your BIOS and manually set the CPU FSB to 133 because it may default to 100 which would be causing the CPU to perform slower than it should.
The 2500+ XP is a really good overclocking CPU, but you'd need a much better board being that that one only supports 266FSB