This morning I sat my 70-270 exam (XP pro) and boy, was it a though one! I managed to scrape trough with 922 points but that took work! Also, something funny happened, I got the same question twice.
I prepared for it with the MS-Press book a transcender CD . My strategy is always to read the book, write a summary and then take a test examn, study what I did wrong, take another, etc.. Usually 4 test examns is sufficient.
Despite other people's opinions up until now I had the impression that transcenders were a decent way to prepare for an examn. Not for this one! The transcender questions are hopelessly outdated, a large part seems to come directly from the old 2000 exam.
What to study:

• Basic TCP/IP
• Policies, what they can do and how to check if they are applied and how to force them onto a machine
• All the different ways to install and upgrade XP
• PXE booting
• Printing (spooling, queues, operating rights, pooling)
• Dial-up networking
• ICS
• Firewall
• Remote assistance and remote desktop
• What rights are needed to install hardware (printers, removable media devices)
• IIS and especially the limitations of the XP implementation
• Encryption and what you can and cannot do for a user
• Offline files
• Disks, basic, dynamic and what you can do to extend them

I'm glad it's over. In my opinion it was a lot ground to cover in a single exam. Also, 58 questions is rather a lot. Anyway, I passed it and with my old NT 4 MCSE this should make me MCSA certified now.
Next exam: 70-284, Microsoft Exchange!

Update: According to the friendly people at Transcender next time I should try and get the exam from their site instead of from the CD.