Did a Google search and then over to Realtek website for a driver.
The sound is back...
But, please, the question begs, what does it mean, "The Currently Installed Sound Card Does Not Support Direct Sound Input, recording audio is not possible"
I am just actually amazed that 1.5 runs on the system you have.. let alone you may have a little issue such as a sound card one!
I would suspect its to do with drivers.
Sure hope it's not a 1,5/Win thing.
But it is highly likely. Revert to XP32 and try again or upgrade to CS4.
First thing that I would do would be to install the latest Realtek drivers. You will need to go to the Realtek site to get these.
Next, in PrPro, there is an Edit>Preferences>Audio Hardware setting page, with the additional ASIO Settings (at least in PrPro 2.0 and above). There you can set how PrPro handles audio. If you still have issues, I strongly recommend ASIO4ALL. It is freeware, and easy to install. Once installed, one goes to the settings pages above and choose ASIO4ALL for everything. This little driver has worked so well for people with lower-end sound hardware, up to true esoteric hardware, at the very upper-end of the spectrum. I cannot count the number of music editing professionals, who have been helped by this little free driver. I use it on my Creative Live DD 5.1 SS card, and it works perfectly.