Hi,
The methods suggested by Carltos Cool both depend on the driver already being installed. In other words, that is what you should do
before you reinstall Windows, while still using the old installation that (presumably) has all drivers installed.
If you didn't have such foresight and it is too late, there are three things you can do:
1) Use some software that actually scans the bus and identifies PCI devices. My recommendation for that used to be Lavalys Everest, but they've since discontinued the free Home Edition. While looking for a replacement, I found
this -- it's a little rough around the edges, but seems to work fine.
2) If your sound is built in your motherboard, then your goal should be to identify the motherboard rather than the particular sound chipset.
This handy little program usually does a good job at it.
3) Physical examination -- this requires opening your computer, looking at your hardware for some identifying markings, then putting that into
to find out what exactly it is.
For example, here is a picture of a Creative SB Live! card:
Notice the main chip says "Creative" on it and there is a model number in the upper right corner. You should be looking for hints like that, then googling them. If there is nothing relevant on the circuit board, try some numbers from the main chip.
If you have onboard sound, you can also use the same method to identify your motherboard. The motherboard model number is usually prominently printed on the board somewhere and easy to notice; they tend to be short strings of letters and numbers (for example, "P4C800").