Root 2.2 to 2.3?

[cushphil]

Hi all, I am new to android I have an Aria which is running Froyo I want to use a custom CM7 Rom so I am trying to root my phone I have done what the guides all say to do ie debugging etc etc and when I run unrevoked 3 I get the following error msg. Error:failed to get root. Is your firmware too new. Any thoughts on how to get past this and get my phone rooted? I want to run the gingerbread CM7 rom to try and help my phones speed and battery life a bit. Cheers guys. Oh also will that CM7 run live wallpapers like 2.2 and are there any disadvantages to using it over using the factory 2.2? Thanks.