Static with USB Headset

This is my first post here & i apologise if its in the wrong category & what not.

Well i have a Logitech PnP USB Headset & the sound is superb, however i have an issue with voice conferencing on MSN. My friends often complain that there is a lot of static/random noises when we voice chat, im not sure what it could be because when i record a test file the sound quality is very good.

I have recently got a new pc with Vista 64 bit, i were previously using XP Pro 32 Bit with no problems. Could this be the reason for the voice quality?

Ive played with settings and whatnot to try figure this. I have a decent sound card but im guessing that doesn't matter with this been USB (ive tried plugging the mic into the card using the jack with same results in quality).

If anybody has any suggestions or ideas why this might be happening any help is appreciated or if theres some sort of utility to help.

Thanks in advance.