the XP line is a quite older chipset than the X2 or 64 line. The former is 32 bit and achieved 10 generations with the last XP CPU being the 3200+ XP. The latter two are 64 bit capable but normally run in 32 bit mode as windows XP standard is 32 bit. Few software developers, drivers, or OS support the 64 bit mode, but there are some.
The XP CPU line is still quite fast, even with today's standards, but it is getting long in the tooth and it is a single core processor. The 2500+ XP line was famous for being quite overclockable before AMD wised up and locked the mulitpliers in later releases.