How to install virtualbox guest-additions for ubuntu 10.10:
http://www.sysprobs.com/maverick-meerkat-ubuntu-1010-virtualbox-328-ubuntu-1010-guest-additions-fix

How to install node-js from source on ubuntu 10.10:
apt-get install build-essential linux-headers-$(uname -r) libssl-dev
tar -zxvf node-js and then ./configure make and make install as per instructions

Don't worry about  port.h, sys/event.h and kqueue missing, they are conditional operating system instructions that may or may be missing on your system, configure is only doing a system check to know how to compile (make) your nodejs version.
Nodejs v0.2.4 installs properly on 10.10 with no issues. (6.10.2010)

How to make a virtualbox Ubuntu guest visible from a Vista host:
1) make sure that the network properties from vista (the host) of the virtualbox host-only ethernet adapter have the "virtualbox bridged networking driver" checked

2) set up the vm like this: two network adapters, leave the first one for NAT if you have it already (for browsing worldwide internets) and set up a second as "Bridged network adapter" choosing your virtualbox network adapter (not your real network adapter, even if it may work like that too)

3) add the correct metadata to your virtualbox (see http://mydebian.blogdns.org/?p=148 and http://data.agaric.com/node/182)

4) start the guest, configure eth1 (system/preferences/network connections/ -> wired -> auto eth1 -> edit -> ipv4 settings, method manual) with the virtualbox host driver network address (192.168.56.1) and netmask 24 (255.255.255.0).

5) start nodejs with a server listening to any address (if you use hello.js remove the binding to '127.0.0.1') and the guest-port property you configured for your vm in step 3)

6) connect from windows to your virtualbox instance (in my case: http://192.168.56.1:8124/)