To answer some points: yes, the computer is cheap. When I bought it in 2009, it was only $500. The laptop is a Compaq Presario CQ50, which originally came with Windows Vista Home Premium (now upgraded to Windows 7 Professional, the latest it's able to run). My graphics card is an Intel Pentium Dual CPU T3200 @ 2.00 GHz on a 64-bit operating system. As for the RAM, you're right on the money:
It seems that I'm too poor now to be able to play games on it.
Do external harddrives come with their own RAM or do they feed off of the computer? I'm just wondering if changing the game's storage area would improve performance. The answer to that is most likely no, but I'm asking anyway.
The above statement that external drives don't have RAM is not completely accurate, since they - as almost all external devices - have a small memory for caching data and for programming the motors and stuff. But it's usually not called "RAM", even if de facto it is. But no, they don't access the computer's main memory in any way.
Hard drives, USB sticks and stuff are 'external devices', they communicate with your computer through read/write commands and don't care at all who gives the command. They don't know zip about your machine.
What bothers me most, is that you have a 64 bit system running on a 3GB machine, that's quite suicidal. Usually I would recommend to switch to 32 Bit, but people now start to only release 64 Bit versions of their programs, so these would not run on your machine at all in that case.
Let's face it, your CPU is slow as well, but I think the biggest problem for your machine for low performance games and applications
is the main memory. If you know someone who knows a little about Laptops and is aware that there are different types of memory modules, visit him and let him check if it's possible to put more RAM in your machine. If not, then visit a local store.
Since it's so old, the modules usually only to be found on the second hand market, many times you'll have to buy on Ebay from chinese sellers who make a living from buying old hardware and sell to people like you (or me, I put more RAM for page caching into my network printer, had to order it from China). They are not all too expensive however. Depending on the model (the memory module, not the laptop) it's possible to get 8GB for 40 to 50 bucks.