If it use ddr3 then it should use any ddr3 modules that aren't over its capacity limit.
You can use two 2GB sticks at 1333MT/s. most times when buying RAM MT/s is misleading written as MHz. That doesn't matter.
Its affordable and Crucial is a reliable company.
You need a 64 bit operating system to make full use of 4 GB of RAM. If you have a 32 bit (which is the default on you machine) you will need to upgrade and that isn't free for windows. If you only want 2GB of RAM (which is double the default, 4GB is quadruple) then that won't be a problem and you can get this instead:
In the specifications for your computer your motherboard and CPU support 2GB modules. Something is wrong. You may have a bad module, installed it in the wrong slot, forgot to reconnect your hard drive if its been disconnected, or a number of other things. Make sure every cable that should be plugged in to something is plugged in and that when you install the RAM module it is all the way in.
My only guess is that your hard drive is unplugged and since it isn't attached your computer can't boot. There are two connectors for your hard drive drive one is for power the other for data. If one is unplugged then the hard drive won't work and if it doesn't work then you can't boot to windows because windows is on the hard drive like all your data.