How to upgrade to from 1.51 to 2.0

I read how to downgrade from 2.0 to 1.0 to 1.50. Please help what is the exact process of how upgrade from 1.51 to 2.0 step by step where to copy the file. Where can I find that file & is there 2 different file for 1.51 & 1.52 users to upgrade to 2.0 my friend have 1.52.

One thing more I read like GTA & other new games upgrade PSP to 2.5 ROM when we inserted UMD in the drive after run so what to do to stop this upgrade.

Thanks in advance.

Best Regards,

SOHAIL

to upgrade to 2.00 fromm any previous version, download the 2.00 eboot, http://www.psp-hacks.com/download.php?id=6
make a folder in (PSP DRIVE):/PSP/GAME/UPDATE, and put the eboot.pbp in there
then run it off the game menu on psp without a UMD in