Compatibility Question for CPUs and Motherboards

Hello,

I am new to these forums and I had a few questions. I am very new to computer gaming but have been around computers all my life, I have a basic desktop computer which has an ASUS M4A77TD Pro and my Processor is an AMD Phenom ll X2 550. I have 4 GB RAM with an ATI Radeon HD 4300/4500 Series Graphics Card and a Seagate 1TB HDD. My computer is a piece of crap I know lol but I just want to know in any of the gamers with tech knowledge If my motherboard is actually worth adding on a new processor and GPU/RAM and all that jazz or and I better off junking it and buying a newer motherboard with all added bells and whistles. I will be mainly using this computer for gaming but also will be using it as a home computer aswell when I am not gaming Ex: I will be surfing the web, watching movies etc. all when I am not playing any games on it. In your experience with gaming computers what would be the best possible option in my case. Also, I am not made of money, I will be building my gaming pc little by little. I want to know what is the best bang I can get for my buck. Even If I do have to throw out my motherboard, what are your suggestions as to any possible deals on computer parts. I live in a fairly remote area in Canada so while I can get things shipped I would have to travel 45 minutes to go pick it up, I would rather prefer to get it mailed to my P.O Box so I dont have to travel for each individual thing. Just something to keep in mind if you are going to give me some links to certain websites so I can buy online. In advance I would like to thank anyone who helps me, I really do appreciate it!

Thanks again,

Larry T.