Firefox memory leak and virus attached to svchost.exe?

Alright, I have two problems that have been bothering me for sometime.

Problem 1:
I'll start with the firefox deal. I have the latest version of FF2 (version 2.0.0.14) but I have noticed that after about ten-fifteen minutes of browsing, firefox tends to take up an unbelievable amount of memory, as in over 100,000 K, and thats only after ten minutes. Pretty much any time I browse the internet, task manager lists it as the process that uses up the most resources. Hell, some games don't even use that much memory. I understand that browsers tend to use up more memory the longer they are run, but it shouldn't be that bad after ten minutes. Any specific ideas, or should I bring this to some firefox help support forum?

Problem 2:
As for the other issue, I have only ever noticed this after coming out of hibernation. Upon coming back to my desktop, one of the svchost.exe's that are running jumps way up in memory usage, to about the same numbers I listed above (between 80,000K-100,000K), and won't come back down. I have noticed that after ending that particular process I tend to lose any capabilities for my sound drivers to work (none of my media players can produce audio output, although I believe that Windows retains the various system beeps ), forcing me to reboot. Not that big of a deal, but this is more of a hassle than I would like to go through everyday. This sounds kind of like a virus has attached itself to that articular svchost.exe, although Symantec has never detected any such problems. Would a HijackThis log help?

Thanks for any responses!