Absolutely. These were the newest processors available when Windows XP was released.
Windows XP runs on any x86-compatible processor starting with the Intel Pentium.
The Xeon with EM64T and Pentium 4 with EM64T processors
You can install Windows XP on your Mac with pentium-3.
As an absolute, that may never be known. Officially, Windows XP requires a 233 MHz Pentium processor. Experiments conducted by various people have run Windows XP on processors underclocked to just 7 MHz.
Windows XP Professional supports up to two processors
YES
They are "compatible" in the sense that many applications that run on Windows XP will run on Windows Vista.
Windows 7 is capable of running on any x86 or x86-64 compatible processor that runs at at least 1 GHz. This includes late-model Pentium IIIs, Pentium 4s, Core, Core 2, Pentium Dual-Core, Core i3, Core i5, Core i7, Xeon, Athlon XP, Athlon 64, Athlon 64 X2, Phenom, Turion, and Opteron processors.
Yes, Windows Live Messenger 2009 is XP, Vista and 7 compatible.
Officially, Windows XP requires a minimum of a 233 MHZ Pentium processor. Unofficially, with a minor patch or via hard drive swapping, any Pentium processor can be used.
Yes, if you purchase Microsoft Office 2010, it will be compatible with Windows XP. If you get the newer version like Microsoft Office 2013, it will not be compatible with Windows XP.
No. iBooks use PowerPC processors, which are incompatible with Windows XP.