So, I finally have Boxee running with Ubuntu 9.04. There were a few hurdles to get over, but everything is running smoothly now. Here are some notes in case I ever need to rebuild in the future (Ubuntu 9.10?).

Tip 1: Disable pretty graphics from the appearance control panel. Set to none.
Tip 2: Mount to storage server using SSHFS. 1) Send root's and the 'boxee user' public DSA SSH key to the 'boxee user on server'. 2) Automount SSHFS w/auto reconnect of SSHFS = icing on the cake.
Tip 3: Let boxee alone for awhile so it can index your content.
Tip 4: Don't use Intel video cards. Stick with Nvidia. Cheaper cards work fine. 8400 is a bit too much.
Tip 5: 4GB of ram is cheap.
Tip 6: use 40/80gb drive for client machines. Data will be stored on server. Doesn't needs to be fast either. A slow 5400 is even better. Boot time is still quick. Less noise/heat/electricity.
Tip 7: Find a good sources.xml file for more/better internet streaming content. Need to tackle this.
Tip 8: Disable/remove services you don't use/need from Ubuntu. IE: Bluetooth daemon if you don't have bluetooth.
Tip 9: Profile the OS bootup to get things started faster. Also knock down GRUB timeout to 1 second, not 0.
Tip 10: ***GET A REMOTE CONTROL*** - OMG - what a difference. I bought a cheap $24 jobbie off Newegg and it was plug-n-play (nearly). Just did 'sudo aptitude install lirc lirc-x' and it just worked! I even put the sensor aimed at the wall behind the speaker and it works. Can't even see the IR receiver.

Hurdle #1: Video goes fast then slow, audio cuts in/out.
Fix: Remove pulseaudio, install esound:
sudo rm /etc/X11/Xsession.d/70pulseaudio
sudo killall pulseaudio
sudo apt-get remove pulseaudio
sudo apt-get install esound

Hardware:
Motherboard - ASUS p5q-em
4GB Ram
80gb 2.5 SATA (Laptop) drive
Intel (duuu) 2.6GHz core 2 duo
8400 nVidia based card

Results:
Nice! Content is stored on my NAS (Network Attached Storage) and everything just plays. HD content playback is smooth and crystal clear on my Sammy 47' via HDMI.