Update Sep 23rd 2010: I am now using (as mentioned in the previous update) ThermoHID with the TEMPer2 device.
Update July 10th 2010:
Finally there are drivers available for Win 7 x64 over at pcsensor.com, so I have tried them - the first attempts were very disappointing though. I have been told by the very helpful pcsensor.com support that my stick is a Serial-to-USB version, whereas a real HID version is being sold since mid-2009, so the newer versions of their read-out software won't support those older models.
Fortunately UTAC (available at Albert's Greenhouse) handles both versions, the serial-to-USB (< July 2009) and the HID version (> July 2009). Let's hope this driver won't cause as much BSOD's as the Win XP version did for me.
I will try the HID only, but very customizable ThermoHID by Steve Timmons as soon as the new TEMPer2 arrives. This one has no humidity sensor but comes with a second temperature sensor, so I can record both in-door and out-door. We will see.
I have ordered a "TEMPerHUM" USB Stick some time ago that is able to measure the current temperature and humidity. Installing the provided driver, NOT using the software shipping with it, but using UTAC 
to capture the recordings and setting up the transfer of the reults to my server was easy.
Here is the current graph (updated every 15 minutes if not configured different in the mean time):
