I'm running Quickbooks on a Win2K guest over Ubuntu 8.10. The Virtualbox and Windows set-up was easy and trouble-free, but I'm finding for the first time - and I've used Virtualbox for some time now in this configuration - that the guest network connection drops temporarily from time to time, causing delayed write errors to pop up in Quickbooks and the program to crash.
Virtualbox chooses for its network adaptor (which I assume is virtual, since my real adaptor is a Realtek RTL8111) a PCnet-FAST III (Am79C973), for which Win2K installs the correct driver, and networking in a NAT environment works fine without any effort from me. Except for these drops in connection. I tried changing the adaptor to the Intel ones offered as a choice in the Settings menu, but I couldn't find a Win2K driver for these. The connection seems to re-establish shortly after it fails, as a re-start of Quickbooks connects once more.