its a bit more work to it then giogio says (no offense meant)
the installer has 2 options
- install with sql 2008 r2 express
or
- install on your own sql server
if you choose the first option, sql 2008 express will be downloaded. I am not sure if the express version can run on the same machine as the sql 2008 server that you mention. I do not think so tho.
if you choose the second option, then you have to point the installer to the sql machine but you have to give in the instance that you want to have avast install its database in. The avast installer does NOT create a new instance, only a new database in the instance that you tell the installer to install too.
if you care about other databases and security, you should installed a new instance on the SQL server (im not too much into sql server yet, so dont know for sure if you can limit windows accounts to access only specific databases in an instance) next to that your development databases instance can be cleaned and restarted without consequences to the avast production database.