If you are looking for XP drivers, try the Sony Asia-Pacific site. They have instructions and drivers for downgrading to XP. I have used these drivers on my US FZ-180E/B and have had a couple issues I am working out but for the most part it has been a success:
Here is a link
Downloads : Support : Sony Asia Pacific
Note the FZ1 series all have similar drivers.... note however if you have Intel Graphics I don't think you will find this their. Use for example the FZ18G model and look at the zip folder version .... the instructions show up in there. Note you are going to have to check if these drivers are appropriate for your hardware on your model. Look at several models and see which one looks the best.
Install order is important.... just follow the instructions noted. Do reboot after each install of each software.... note I had a couple blank screens upon reboot when going thru this..... just wait until HD activity stops and push the power button to turn off and then again to restart and it should recover on the reboot.
Note you do need the SATA drivers while installing XP... I unzipped them and put them on a floppy and used a USB floppy drive (mine was a Toshiba).. You can also use NLite but for me this was easier. Press F6 when requested in the XP install (almost right away) and latter it will ask you to install the drivers... pick the right one.... I think it is the mobile AHCI one.
For getting the brightness buttons to work check here:
Trying to solve the Brightness Problem for SONY, SAMSUNG, LENOVO, HP and TOSHiBA users - nVision
and more importantly here:
Modified LaptopVideo2Go nVidia 32-Bit XP INF with VAIO Brightness Controls - Notebook Forums and Laptop Discussion
I used the modded 169.28 NVidia driver and the separate modded INF to give brightness control. Note you have to replace the old INF file with the new INF file and then install. I did install the original Sony NVidia driver but I used Driver Sweeper after uninstalling it to make sure the new driver install had a clean install.
And for gettting WPA2 to work for wireless you need this:
Description of the Wireless Client Update for Windows XP with Service Pack 2
Note I do have sound but can't get audio over HDMI to my TV to work. Microphone input via the built in mic seems a little low as well. I am also experiencing some Camera Capture issues (bubble pops up to ask to restart the camera utility) but this is minor.
Note, applications like WinDVD BD cannot be reinstalled as they can't be recovered and used in XP (as far as I have been able to figure out)
Hope this helps