Media Center is awesome. If you have high speed internet, it's even better. You can watch live TV and record it. My aunt has it and it's pretty sweet. Way better than Home and it's worth the extra spending.
i dont have access to high speed yet........ but it might be something to consider. is that the only diff ? if so i might just be ok with home for now. then when i do get the good connection upgrade then.
Media Center sells for about $30 more than XP. If you ever intend to add a TV tuner to record or watch TV then it is worth it to pay the the few dollars more. I record weekly TV shows so it had been a great asset to me.