Crackle / Static / Breakup with GXP-2000 - VLANs?

I can't be sure this is specifically a GXP-2000 only issue, but those are the only phones we have. We have about 20 phones that, from time to time, get static, breakup, and dropouts. The computers are connected through the phones. Interestingly enough, we don't seem to get static or dropouts on some phones that registery remotely over the Internet - the issue only appears to occur inside the network. We are using quality 3Com managed switches, but we are not utilizing VLANs.

Is VLANs a recommended deployment methodology for this setup? Does anyone have any experience, or would a network of this small size not need VLANs? Should I be looking somewhere else to resolve this problem?

Thank you!