You have a topic on this:
http://www.pspbrew.com/forum/viewtopic. ... ght=#58427
First of all, dont say you dont know how to search on google for ISOs.
If you want iso's, then pm me for a good site.
And dont use UMDEmulator or Fastloader, you're best option if you want to stay at firmware 1.50 is to use something called Devhook v5.1.
To install, simply go to the Tutorials section on the forum.