The computer you posted is almost identical to the one I had about 10 years ago, except it was home built not a Compaq (I had BAD experience with Compaq computers when I was like 11 and my parents bought it). If you wanted a PC that would handle basically any game made to this date, you need something more along the lines of this:
http://www.epinions.com/specs/dell-xps-8300-intel-core-i5-1000gb-4gb-dxcwmn1-pc-desktop
That is still outdated a bit but it would play SWTOR no problem. Of course I'm not endorsing buying that exact computer(at all), but those are the specs you're looking for if you were trying not to go overboard on price. You could get a similar set up for a lower price I'm sure. Just make sure the processor is dual or quad core, the number 2.8ghz is the speed of EACH core in processor, the 2.8ghz on the one you posted was an old style single core, which means it's actually more around 1/4 the speed of the one posted above.
Upgrading RAM will have little effect on performance (unless you had very little to begin with). After everything else has been replaced RAM will give you maybe a 5% boost at the end of it all. The biggest speed boost for gaming comes from a nice video card, and second biggest would be processor. Of course if your computer is old you'd need a whole new rig to take advantage of new processors and video cards.
Just saying keep those two parts in mind when buying, they are the most expensive parts, but the most important for performance.
I don't know if you actually wanted a solid reply or if you already know this shit, but there it is in simple english. I could have easily written you an article but I stopped myself.
Maybe I should have used car part comparisons.