Hi,
Audio in Windows 7 really shouldn't be causing you this much grief and I'm very surprised that after installing a Sound Blaster card that you are still having issues.
Could you please post back with details of the following:
Which version of Windows 7 you are using and is it 32 or 64 bit? Also is it OEM, Upgrade, Full Retail or crack?
Are you overclocking or have you unlocked your CPU?
Are you using Windows Media Player or other program(s) for Audio Playback?
What kind of internet connection are you using and who is your provider?
Could you also please provide your full system specs as other items that you have (including USB Devices that you have plugged in) could have an impact on Audio playback and the more details you provide, the easier it makes it to help with troubleshooting.
Thanks