Partial page caching

Hi,

I'm not sure if this is the correct place to ask. I need to improve my drupal performance, so I'm investigating possible solutions: boost, memcache, native drupal DB cache etc.
I've a minor issue: some of the pages contains dynamic data, like counters. the counter is a field of a custom node type. And this field can be updated at the database by some other scripts. So, the anonymous user should see the correct counter value even if we have a caching. Actually we need something like partial page / node caching. The page should be cached but that counter should be taken from DB.
Anybody have idea how to achive this?

thanks