I think you may have to move up to 3.6 and then to 4.0 as the agent versions and support changes. 3.5 cannot handle the 3.6agent and also the console has changed in EPO3.6. However this process is going to be a bit long because you would have to upgrade to 3.6 then to 4.0 plus the install of sql2005express etc.
You should be able to export your policies out and import them to 4.0 though.
On the other hand.
It may be a good idea to get used to 4.0 and just go from scratch, basically setup a server and start deploying new agents to a few machines and when you have set up everything and have your policies working in 4.0 just do an install over the existing agent on your other machines as 4.0 comes with the new agent.
Again depends on you, just make sure that you install the agent in the same location used for the previous agent.
Zerious
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