NO WAY. Don't buy that from Alienware. Alienware PC's are good, but they are so far overpriced it's not even funny.
Here let me explain this to you this way.
AU - 5567.99 - 300 MIR = 5267.99
That's 3,864.60 USD
You could very, very easily build that same PC for under $3000.00 USD or 4,089.00 AU. IF you don't have teh knowledge to build you're own, well don't worry, (TF-Members) have helped hundreds of people just like you, BYO and save money. Just get comfortable here and start using the search function. This will bring you directly to many, many threads were your questions will be answered. If you can't find your question, then start posting threads asking questions.
You're best bet would be to stay in this Section.
BTW - XP Home with a highend gaming PC isn't a good choice. XP PRO.