Yeaa, your processor is definantly not sufficient to play TF2 at high frame rates, especially with the new updates. Your page file does seem to be using a bit more than it should, so I would check to see what else is running, perhaps background programs or services, that you can disable. I am pretty sure that System Model is referring to the motherboard model and the specs I pulled for that model suggest it will likely not be able to support a new enough processor and video card to play tf2 well so it might be time to save up for building a new system. Unfortunantly, I couldn't find any processors for your current motherboard that will get you much better performance than you have now, so I can't give you any estimates on how much it would take to upgrade the processor. However, if you want to build a new system you can pick up a decent motherboard for about 50-100, a good enough processor for about 100-150, ram for less than 50, a video card that will do ok with TF2 for 50-100, and most of the other components you can reuse (although I would consider buying some new cooling equipment or a new case if you are burning through memory, it will likely be cheaper in the long run), so you probably are looking at between $250 to 400 (plus the cost of any cooling or a case). A good bet is that TF2 will continue to have updates that will take up more system resources, so building a new computer will probably be the only way to have it run at decent speeds in the future.
As a stopgap until you decide what to do, you might consider overclocking your current computer (if you can). This will be rather risky, but it might be able to hold you over until you can get the parts to get it running fast again. If you do overclock, you should probably leave off the panels on your case though, the cases most desktop manufaturers use aren't very good at cooling at the best of times and overclocking will very likely push it beyond its limits.
