As thebulletfromhell said, the system.img/sqsh file method of installing Android is now very outdated, and the more mature builds are using the Androidinstall.tar method, this method has several advantages, a menu driven installer, easier updating, greater stability, less problems caused by mis-matched rootfs/system/zimage files.
The two main builds at the moment are; Myns Warm Donut : http://forum.xda-developers.com/showthread.php?t=619980
And Polyrhythmics Eclair 2.1 : http://forum.xda-developers.com/showthread.php?t=600154
Both of these are probably the best supported and most widely used ports to Kaiser hardware.
There are other builds of course, but as a newer user of android I'd recommend these two first.
XDA IIi ROM: 1.11.00 WWE Radio: 1.04.0 ExtROM 1.11.171 WWE
HTC Kaiser 1: ROM: Polymod 2.1D Final-Dark : Radio: 126.96.36.199
HTC G1 Dream: GammaFly V1.3 RC2, AmonRa, DangerSPL, Radio 2.22.27.08
HTC Desire ParanoidAndroid 3.99
Polymod 2.1D Final Version: Gone, but not forgotten
Android boot splashes and boot animations
(for Kaiser )