from a tx owner and user:
i have a tx2513cl from costco. I agree entirely that heat is a fierce problem. This thing can get over 90C easily. Though with everything turned down to power saver, you can get back down to ~50-60C. Most likely, the x64 AMD processor is the culprit (and reason for lower price at the same time). The machine came with Vista x32 and I have had very few problems with the OS. Of the few problems, most are minor, but using the external VGA contributes to the heat and will sometimes just shut the whole machine down.
As for hardware, there seems to be some magnet in a small corner spot that throws off the stylus by a few millimeters - not a major deal, but I'm annoyed that it does this. In Vista, I sometimes accidentally touch one of the panel buttons and start up some app I do not want - Media Center stuff usually. In low ambient light, the panel display lights are a bit bright. The 6 cell battery doesn't last long at all unless the display brightness is at a minimum and all other power saving (read: performance decreasing) features are enabled, an 8 cell is available. The touchscreen is also very reflective, which I believe (think ?) to be a problem with a lot of these machines, it can be almost impossible to read when the display brightness is low. I have calibrated the screen maybe three times, and that was just for "fun", as the touch input really is great. When temp is high, the fan can get a little noisy, but not much more than what I've experienced in other laptops.
I upgraded to an OCZ solid state drive and installed Windows 7 (x32) and the thing absolutely flies now. Power consumption is still an issue, though. With 7 the handwriting features see some improvement and the external VGA never fails.
With OneNote (pre-installed), I have found a lot of success using it for a year in college now. I use a SBS 2003 server with SharePoint to keep it synced/backed up. I've not found any other software on the market that can compete with OneNote, though there are probably some competing vendors. OneNote really is an impressive piece of software.
I paid ~$950 for the machine and considering the price and even the aforementioned problems, have been happy with it, more so after the Win7/SSD upgrades. Others on the market in this line were twice that price at the time.
Hope the lengthy input helps!