Optimization Tips

[TaylorDCIS]

I am looking for some advice on how to configure my Express server. Basic Stats:

Express Server 7.0
Windows Server 2008 R2 64-bit
8 GB RAM
823 GB worth of satellite imagery spread out over 6 UTM zones, 28 States, and about 2000 counties.

We have one file set (.sid .aux .sdw) for each county. We are publishing the images to our web application through WMS. Currently, we have it configured with one catalog for each UTM zone and grouped together by one Multicatalog. It takes a very long time to generate overviews and they don't seem to help. Users will almost never be viewing an entire UTM zone at once. A typical view will not even be the whole county. My first thought was to give each county it's own catalog and overview until I realized we had a little over 2000 counties. That would be a lot of entries in the config file and some tedious work for me. My next thought is to have a catalog for each state/UTM zone combination. I would like to get these images served up as fast as I hear they can be. Any thoughts on which configuration would be better will be appreciated, as well as any other advice. Thanks.