You can get external hard drives at Best Buy or Fry's or other electronics stores.
External memory for a computer can be found and purchased both new and used from the online services provided by the eBay, Amazon, and Nextag websites.
You can buy an external mouse and hook it up to your laptop, they can go as cheap as $5-$10 dollars for a mouse. Or if you dont want to haul around an external mouse, you can unscrew your laptop and buy a replacement mouse trackpad, the whole repair is about $50.00-$60.00
To install laptop memory, you will need to first consult the instruction manual. Afterwards, you can buy the memory chip, open up the laptop and then place the memory chip inside.
Inside, you have to open it to see it. You can buy more memory for your laptop at the local computer store.
Yes, you can do it but: If the laptop has a DVD burner slot you just slip it there and it is done. If not, then you want to buy an external burner that is usually connected with Laptop via USB cable.
buy a memory expansion pack
You can buy some Memory Ram from eBay and insert in to your laptop!
Buy an optical external disk drive.
Memory Express.
You can by an external screen and keyboard and mouse.
You can buy an SD card reader which plugs into the USB port on your laptop. The card is read like an external memory device. Here's an address for an example at "Tiger Direct": http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=6634192&CatId=2825
It's easier to keep up with the one in your computer.If you're traveling that's a big advantage.If you're using it at home mostly then it's not a big deal.
Compaq Presario physical laptop memory can be purchased from stores like eBay, Amazon, Best Buy, and Walmart. Physical memory can also be purchased directly from the manufacturer.