Bleh. Especially the part where the company is keeping track of your online activity.
I'm still annoyed at one company that I had worked for. This company used a lot of open source, but since it was modified, they didn't release anything back. Rather than rant over what I went through, I can only offer you a bit of advice. Run like hell. If the company is steadfastly refusing the benefits of Open Source, and this makes you unhappy, it's not a good enviroment for you. Stress is bad. And if the company has identified you as an Open Source advocate, there will be people who will increase your stress.

Here's some links to previous somewhat related discussions: