Yes, I installed the latest 64 bit Realtek driver.
Nevertheless, there are serious audio problems present for both 64 bit WIN7 and XP. The audio is extremely choppy and scratchy at best (OSS). This is not the case for 32 bit XP nor when I run the 64 bit XP/WIN7 natively. I have to conclude that this is a problem with how VB makes host audio available to a 64 bit guest.
For the 64 bit guests I ran some trials to see which of the abailable audio devices (ALSA, OSS, PulseAudio) produced the best sound. To my surprise the outcome was the exact opposite of what was expected. It turns out OSS yields the best (relatively speaking) and PulseAudio the worst. As noted OSS is very choppy and scratchy a problem that plagues ALSA as well, but OSS seems preceptibly better than ALSA. PulseAudio which has been the purported solution in a number of these threads is so bad as to be unusable. Not only are the problems of OSS and ALSA amplified, but it has the additional problem of having a decaying oscillation applied to the sound waves. It's truly bizzarre. Since PulseAudio works fine with all other applications I once again have to lay the blame at VB's feet.
FWIW, my host system is 64 bit Debian Squeeze, kernel 2.6.32, i7 920 CPU.
I'm hoping that some constructive suggestions will alleviate the need for a bug report.
Thanks in advance.