@Barren

Like Kronos said, 2GB is supposedly possible with the last board revision 2b5, if some criteria are met:

"2GB criteria" collected from discussions on powerdeveloper.org

Also (like Kronos said), Firmware isn't like OS's or applications, where "it's always best to upgrade to the latest version". Firmware is *not* universal code, it serves as a glue between the electronics and the low level functions in the OS, and it is often hardcoded for explicit board revisions. There is no way to add features not supported by the HW by upgrading the Firmware, so a new Firmware would not magically make your non-2B5 Pegasos motherboard work with 2GB memory.

Here is what Wikipedia say about the different board revisions/firmware builds:

https://en.wikipedia.org/wiki/Pegasos#Firmware