I bought a SteelSeries 5Hv2 USB on ProGaming Computer. It’s a nice headset and comes with a USB soundcard similar to the SteelSeries Siberia USB soundcard.
According to the website, it had drivers for Windows XP and Windows Vista but no support for Windows 7. I solved this problem by installing a beta driver available at the SteelSeries blog. Other people reported success right-clicking the driver installer and selecting to execute in Windows Vista combatibility mode.
Now you just need to download the official Windows 7 drivers at the manufacturer’s website.