If you have the money, you should buy a brand spanking new one.
Depends on what your budget is, get a new computer if you have the money, or stick to ol' ancient over there.
I suggest you go for the upgrade . But before buying new parts , check with dell if your motherboard supports them .
Only buy RAM if there is space for adding more RAM and if the motherboard supports it .
Most internal graphic cards cannot be changes , if there is enough space in your laptop with a free post then only can it be changed . If you have an intel graphics accelerator then you need to check with dell if you can upgrade your systems graphics .
If you want to upgrade the processor too , then I suggest getting a new motherboard and build your new laptop with only the old casing and save some of the old RAM too.
All the best .
I would say that you better sell it and get new one.
I suggest you sell your main one and buy a better one worth 1000$.
You should just upgrade your graphics card and get a new processor.