Given that I got my laptop over 3 years ago and it's currently out of warranty, I thought it might be a good time to start looking at upgrades. I still don't have any real gripes about my laptop - it's performing incredibly well for being over 3 years old. The only thing I'd really like to upgrade is the video card and have multiple DVI outputs (instead of a single VGA).
The biggest thing I'd like to try is a Tablet PC. I've been intrigued by them since they came out, but I've always been concerned about their durability. I've had a number of laptops - some IBM 486, some IBM Pentium, an IBM Thinkpad 390e, an IBM Thinkpad T21, and currently an HP zt3000. My biggest concern has always been portability and secondarily with durability. I've seen a number of laptops where the LCDs' mounts to the laptop just wear out and pretty much snap off. I would think this would be a major concern for Tablet PCs where the primary LCD mount is very small.
The other problem (of course) is Linux support. While most things would probably be okay (scrolling, general clicking around), more support would be very nice. An on-screen overlay keyboard, perhaps gesture support. Some tablet-pc-centric programs like something for taking notes. I would also have to make sure that XRandR works properly with the LCD and video card (and hopefully can be automated at some point).