If your pc can boot from network you can setup a pxe boot server on your n900. i did it some months ago to install the lucid beta on my netbook.
Unfortunately i have bricked my n900 and didn't backup the files.

Edit: Cool, i had a look again and the files are still there actually!

Just tell me if you want a tar of the pxe server - i can put it on a server for you. It has FreeBSD 8.0, a pre final version of Ubuntu 10.04, memtest and clonezilla included. You would have to extract a newer ubuntu iso into the pxe root and fire up dnsmasq as dhcp and tftp daemon.