Is there software out there than can recommend what PC component to upgrade?

One way you can do this is going to this website here and choosing a game you would like to play from the drop down menu then it will install a free software that will tell you if you computer meets the requirements or what needs to be improved to meet the requirements:

http://www.systemrequirementslab.com/cyri/

You can also use the windows experience index. In vista you access this by right clicking on computer in the start menu then click properties and next to rating you'll see windows experience index in blue click on that and you'll see the different scores for each component in your computer. This will help you find the bottleneck in your computer.

For gaming:

1: RAM.

2: Video card.(*)

3: CPU(**)

* Be sure your power supply can handle your video card.

**If you're considering #3, it's probably time to just get a whole new system. A new motherboard will have a faster bus, and will support faster RAM - both of which will give your game performance a boost. I like the boxes that Velocity Micro puts together (velocitymicro.com) They use off-the-shelf parts so its easy to upgrade your box later on, they will overclock, tweak and maximize your configuration's performance, they give you an actual OS CD (most places won't do this unless you ask - which is wrong!) and they don't junk up your computer with a bunch of trial software or other garbage. You only get the OS and that's it.