If you have XP, I think there is no reason for using 2K. It is indeed very similar. The reason for XP was replacing ME and get rid of old 16 bit DOS after all. In order to do that, they basically took 2K, beefed it up with some new and unnecessary wizards, some optical knick knack, and call it XP.
I used 2K quite some time. Pretty much every software for NT and XP used to work just fine, until Microsoft discontinued 2K support.
Especially software compiled with later Microsoft compilers refuse to work, while software from competing compilers continue to work, unless they depend on other Microsoft libraries released after the 2k discontinuation that is. Sadly enough, those incompatibilities seem to be pure marketing decisions rather than technical reasons, ie. planned obsolescence.
And about the phone home/activation issue: AfaIk, 2k did this already, but didn't inform the user about it. After complains from privacy advocators, they introduced the activation wizard in XP and other software.
DOS-PC: DFI k6bv3+, Pentium 200mmx, 64 MB RAM, Terratec Maestro 32 sound card, Roland MT-32 + SC-155, Winner 2000 AVI 2MB, Voodoo 1, Win98SE
Windows PC: GigaByte GA-MA790GPT, Phenom II X4 905e, 12 GB RAM, M-Audio Delta 44, NVidia 1060 6 GB, Win7 pro x64