Your system can still perform decently at this moment (if it is still working a.k.a not yet broken or facing instability issues).
Your system is a bit old but not yet ancient and not really out of date.
I think your system is still OK.
You can try considering an SSD for an update, and OC your system.
See my system for reference, it should have about the same age as yours (except for the SSD, PSU and GPU), I plan to get a new proc, mobo and ram somewhere next year, during sommer or perhaps later.
I'll be using it mostly for gaming :] Also, would it be better to OC the CPU with a program or manually?
Basically the budget doesn't matter (I just want it to be up to date, sometimes it seems like my PC is waaay to slow).
Bang a Flash/Zip drive in a suitable usb port, dedicate it to readyboost and never take it out without safely removing hardware etc etc,
remove windows components you dont need (Like you did with aero)