QUOTE(miyster @ Sep 16 2006, 03:30 AM)

is it possible i could ruin my psp if i do somthing wrong ?
and is there no homebrew that works on v2.0 ?
Yes it is possible than you could ruin (the term is "brick") your PSP if something goes wrong.
However, it is very unlikely using that method.
And there isn't much homebrew that works on v2.0 (there is some).
Personally, I would say that it is worth the risk (the reward is very high).
I've used the 2.6 downgrader twice, the 2.71 downgrader and the 2.0 downgrader (in the link I gave) on various PSP without bricking any of them. Out of all the downgraders, the 2.0 one is the safest as it actually runs the official Sony 1.5 EBOOT.PBP update file.