First Here are my System Specs:
Gateway GT5228
Memory: 2 GB DDR2
Processor: Athlon 64 X2 4200 2.20 GHz
Capacity: 250 GB
Power Supply: 300 watt
Video Card: Integrated NVIDIA GeForce 6100

I'm looking to add 2 GB of this memory:

http://www.newegg.com/Product/Produ...

And I'm looking to add this Video Card:

http://www.newegg.com/Product/Produ...

I would just like anyones feedback if these are good choices before I order them. I've never added these pieces before, so if anyone has any suggestions please let me know. Thanks!!!

See response 5 in this for some info about ram compatibilty, and some places where you can find out what will work in your mboard for sure:
http://www.computing.net/hardware/w...
Correction to that:
Mushkin www.mushkin.com

Specifically, you would have to determine whether that ram with the module ID string
F2-4200PHU1-1GBLA will work in your mboard for sure.
If you can't determine that, don't buy it - get modules you can confirm will work.

Your PS capacity is very much at a minimum, if not outright inadequate, for supporting a system with PCI-E slots and a PCI-E card in a slot, especially if the card requires a separate power connection from the power supply and draws more than minimal power from that - 430 watts or more would be much better.
Take a look at the manufacturer's web site at the specs for the card model - sometimes minimum suggested PS capacity is stated in video card specs.

If your Windows is 32-bits, forget about shooting for a 4GB RAM system. Anything over 3GB will not be made available for your use.

i_Xp/VistaUser

As stated by XpUser, anything over 3GB is basically wasted on a 32-bit OS. Either add another 1GB (2 x 512MB) to what you already have, or just leave it as-is. DDR2-533 RAM is the wrong memory anyway...you should have DDR2-800. If your Gateway came with DDR2-533 (which apparently it did), your systems performance is suffering because of it. At Outpost.com, you can usually find 2GB of DDR2-800 for less that $40 (after rebate).

The video card you linked to is a good choice but as Tubesandwires pointed out, your power supply is most likely inadequate. Rather than getting RAM, I suggest you invest in a 500W (or higher) PSU & plan on spending at least $50 before any rebate is applied. Here's one possibility:

http://shop3.outpost.com/product/47...

Do you 'really' need more than 2gb of RAM? Very few people do.