Is the memory in your PC a) 2 x 2Gb modules or 4 x 1Gb? Speccy will say in the full report under the RAM section. This will determine if you would need to a) add two more memory modules to make 8Gb or replace the lot. Replacing all of them is obviously more costly.
In terms of priority, a new video card would make the most immediate improvement to games, while I suspect extra RAM would help more with performance while editing large video files etc, if you have a 64 bit O/S. Almost any modern video card from $100 up (e.g. R7-260X or GTX 750 level) would be a worthwhile upgrade. $120 would get you a R7-265 or GTX 750 Ti while some R9 270X's are currently selling around the $150 level. GPUBoss allows you to make a quick comparison between different cards (bear in mind some of the info on that site should be taken with a pinch of salt though).
An SSD I would class as a nice to have.
"You are tearing me apart Lisa"....
Oh and yeah,
It's got 4 sticks of 1 gig memory (all slots filled), so I'm guessing I have to take them all out to put a 8gb stick in there if I want to upgrade the memory?
I think I'm going to hold off upgrading and save for a couple of months and just spend $500 on building a tower. I've been looking at websites that guys are just giving lists of parts to build a complete tower for different price ranges.
Building doesnt seem too hard, but it's a little scary, but when I compare what I can build for $500 to a pre built tower that goes for $500, there is a large jump in quality.
But then again, I'm looking at retail stores and dell direct. Am I missing something? Is there anywhere where you can get a tower built for the price of parts? Or close? I wouldnt assume so, but it's worth a shot.