I would say an SSD would help you in load times for sure.
Looking at your
* SPECS * , I see your current HDD is 7200 RPM (seems they all are).
Most people get SSD's from unprotected se..hold on, most people get SSD's for Windows, and most apps on an HDD.
Your HDD is decent, and program loads are probably mostly alright. Your next big kick would come from a CPU upgrade.
Looks like there was only one motherboard for all versions of that box, and you could go from your current processor to an
Intel Core i5-670 3.46 GHz. You may need a BIOS update, but I believe it would support it. Look into that, and see if you
can source it on eBay or something.
Finally, I'd look at at getting a GPU.
Your specs say the system not only has one motherboard for every variation, but also one power supply to handle every configuration.
They offered one running a GPU close to 60 watts, so that's at least the extra power consumption vs your current set up would support.
You can get a GTX 1050Ti (or low profile version) that will draw a maximum of 75 watts off the PCI-e slot you have vacant.
It should be okay. The benefit would be the faster processing speed of the new GTX 10xx series,
as well as a huge memory bandwidth increase (38.4GB/second vs 112GB/second)