I know what you'd like to hear, but the truth is you should start from new.
Your CPU, GPU and RAM specs are all below the recommended requirements to run this game comfortably.
Your CPU is below the minimum requirements as well as the amount of memory you have (although your video card meets the minimum).
If the Aldi PC you're thinking of is the one I'm thinking (the one for £949) of it would be a good base to start afresh from.
If you upgraded the GPU and RAM in your current PC the CPU would be the bottleneck. If you upgraded the CPU (your board could take an FX8350) it would still bottleneck with the newer video cards on the market.