Upgrading Ram

Alright this is the computer I currently: HP Pavilion a320n Specs - DealTime

Blah I know; what I want is more ram and wanted to know what kind should I buy and if possible at Best buy so...

Anything here thats usable for my computer? Best Buy

This one looks close right? PNY - Optima 512MB PC2700 DDR DIMM Memory - D512MPC27OPT-BB

PNY - 512MB PC3200 DDR DIMM Memory - D512MPC3200

Also plan to buy this if it's a good idea? Hewlett-Packard - 20x Internal Double-Layer DVD±RW/CD-RW Drive - dvd1040i

I don't know much of computer hardware.

Jam it back in, in the dark.

You have to be careful, even if it's just RAM you're getting.

I've ran into problems with this before. The first thing that happened was, even though I did get So-DIMM memory for my now-dead laptop, it was DDR2, but the sticks wouldn't properly fit into the designated slots because they're meant for DDR sticks.

Not only that, I figured later the RAM had to be DDR 400 MHz PC 3200 So-DIMM. You just don't want problems like memory leaps/skips when you run the computer, otherwise the sticks won't like the OS, hard drive or video card they're working with for example.

Ask HP what kind of memory can be installed in your pavillion desktop to narrow down any potential problems. Get your stuff from tigerdirect.com, newegg.com or zipzoomfly.com, if you want.

There's nowhere I can't reach.