Conundrum - hard drive failed, what should I do ?

The XPS M1530 I have ordered arrived promptly this Wednesday. Unfortunately, the hard drive stopped working after a couple of hours. I called Tech support and they agreed to send a new hard drive by courier on Friday.

The hard drive did not show up. I got several calls from Dell and was given 2 options:

1. Dell does not have the HDD (320GB 7200RPM) in stock, I can wait till they do, but they can not give me any time frame as to when.
2. They can order a replacement brand new computer for me with exactly the same specs, this will arrive within 10-14 days. This offer is only valid for today. I was also told that the 7 days return policy would hold for the replacement computer as well.

I know this sounds odd, but this is all the information I have. I took the second option, but I would appreciate some advice. What should I do ?

1. Should I return the computer ?
2. Should I wait for a replacement ?
3. Should I insist on getting a replacement hard-drive (perhaps with lower specs) ?

Thanks