That runtime error only happens with 32 Bit operating systems, because they have a RAM usage limit like 3GB. However, PCs with 64 Bit operating systems don't have that limit, so they can use the full capacity of the installed RAM. So even if you buy memory for your PC, it won't help much, because as I said, only a part of that memory can be used with 32 Bit systems. The only real solution is to buy a computer with 64 Bit operating system (that has enough RAM of course.).
Hope this helps.