But I play one on tv... ;) When I read my various friends' blogs, I find them to be slooooow, but then again they're usually on LiveJournal or something else as well known.
A couple of thoughts, for what they're worth:
1. How often would the networking org site be updated? If you can do simple html, and the site updates only a couple of times a month it might not be worth a blog. But then again, a networking org, I guess, would have calendars, events, etc. If you wanted, you could probably code one yourself, or download some pre-made software.
2. For the work blog, would it be internal only, on intranet servers? If so, you probably would want to go the route of an out of the box install, since you'll have control over the servers. Google 'content management systems'. A good selection can be found on Wiki:
http://en.wikipedia.org/wiki/List_of_content_management_systems . A lot of them are free.
I happen to work in content management, mainly on document management, so feel free to ask me anything!
ETA:
If you work for a larger company that has Microsoft software licenses, you could also look into Sharepoint server.