[dba-Tech] Firefox and Thunderbird question

In Firefox I cannot visit any site that has a Flash intro and view it 
correctly.
In Thunderbird I cannot see HTML email as it should appear.

I guess that I'm missing some plug-ins, but I've tried adding plug-ins 
and it just tells me there are none available.

Any suggestions from users of these products as to how to fix the problem?

I'm running WXP on this machine, with all the service packs.

TIA,
Arthur