In short. No, you can't really upgrade it. The more involved answer is that any money would would sink into upgrading this could be put to a much much much more powerful machine (even a self built cheap computer). Because it is an OEM PC (Dell) the processor upgrade path will be very very limited if it even exists, and you will pay way too much for whatever processor you could drop in there. Second, Dell tends to use non-standard motherboards (Not ATX) so mounting a new motherboard in the case is very likely not possible. Sadly you are going to have to let this computer go if you want a faster machine, there isn't much you can do for it at this point.