Can/Should I still upgrade or a new build would be better?

[MCKejml]

Hello,

I am thinking of upgrading my PC, although last time I checked I had the some of the best things my motherboard could have connected, as it is fairly old. This is my current setup:

Motherboard Model: ASUS M4N78-AM
CPU: AMD Phenom(tm) II X6 1055T Processor // Cooler – AMD 64 box
Ram – 2x2 GB PC26400 AM1
Graphics card – Sapphire Radeon HD 7730
FDD: 16 in 1 apacer sln4123
HDD
Seagate 250 GB sln E78C
Seagate 1 TB WDC WD10EURX-63FH1Y0
Cdrom – DVDRW LG sln 5393
PSU: Seasonic (Energy knight) SS-500ET T3 500W BRONZE 80PL

Can I still add something better on my Motherboard than what I have?
Or would it be better to buy a whole new PC/Motherboard (and which one? Meaning MB.)?
If so, what is worthy keeping so I don't have to buy everything new and connect it to the new PC/MB?

I use my PC mostly for gaming and browsing. I don't use it as a server or for graphic design.

Thanks a lot, guys.

 

[CountMike]

MB+CPU+RAM are already maxed out, only other thing would be slightly better GPU. Other than that, hello all new system.