I changed the HDD. As for the GTX 560 Ti, I can't really change it from the GTX 560 since I'll be going at least $30 over my budget (darn my High school budget for being so tight). The PSU is only for 1 card. Once I can afford a 2nd card, I'll get a new PSU as well.
Most manufacturers make them if you want a "future-proof" GPU. They want to make sure you have enough memory for games that may be too demanding in the future. Even now few games ARE demanding when it comes to GPU memory (GTA IV for example).
Your Thermaltake is really only good to 420w or so, and the extra cash should be set aside for a new PSU for that future HD 6870 CrossFire (when the cards get down to $130 in the next 4 or 5 months due to the new 7XXX-series rolling out).
I'll pass on the X4 840. I had a bad experience with OCing it and keeping it stable.
I already decided to get the Samsung HDD.
The cooler seems great, I'll get it.
Maybe I will get the 6870 or stay with a 560 Ti; I don't know yet.
I'll see if I can really get a new PSU.
Thanks for the advice, I'll see how well it works!