Several things of note, based on this list:
1. I see TeaTimer is running, so you're using SPYBOT. There is a known 'conflict' with SPYBOT and IE8. See Spybot's website for more details of the issue and how you can address it (by disabling all immunizations). This may possibly be one of the reasons for the slow browser performance.
2. You're also running SQLSERVER. By default SQL will chew up any and all memory you have, unless you specifically configure it with memory limits. This is probably your memory hog. Unfortunately, I don't know enough about SQL SERVER to tell you exactly where to go to set those limits or what limits you should set. Perhaps if you leave a message in the SQL forum, someone can help you with that part.
3. You're using Crystal Reports. In my experience with old versions of this app, CR has had issues with releasing memory when done. The longer you leave the app running, the more the chance that you'll run out of memory, even when the system shows plenty of RAM available. It's quite possible that they've addressed this in newer version but, personally, I would make it a habit of either restarting the application often (as opposed to leaving it running all the time) or just plain restarting the computer often (if feasible in your environment) to try to flush memory and reclaim those lost areas.
Hopefully one or more of these observations is helpful to you.