Advise Between 2 PC's: Dell XPS 8300 X8300-4906 vs Systemax SYS SG-103

Dell makes a far superior PC than Systemax in terms of reliability and support. Far better......

What are you going to be using it for? Building your own PC will always be cheaper than buying a complete one pre-built. Often, depending on what your doing, 2TB can be too much, and a 1TB storage will do just fine. I'd also recommend trying to find one a computer with two drives, with a one drive having a single platter for the OS - as it has a lower seek time.
I'm not entirely sure, but i think the 560ti has better performance than the 6770.

You can never have too much storage (2TB vs 1TB). Also, the one vs. two drives advice is debatable at best, as is the dicsussion regarding single platter drives.

Regarding the video prowess of the 2 offereings, the 560ti is definitely the stronger of the 2. However, Systemax still builds junk.

Building (I agree) is the better option here.

1) The Systemax video card is a 550ti, not a 560ti.

2) I really don't need the Blu-ray, since I have free-standing Blu-ray in the same room hooked up to my monitor. But if it's already included, I'll take it.

3) Not really playing any games. I just want smooth streaming video from Netflix, youtube, NFL Replay, NHL CenterIce, etc. Plus muti-tasking & fast web surfing. My internet connection is superfast but my old PC is the bottleneck.

Also, I've never built before. I don't have the time or the know-how. If something dies, I want to just use my extended warranty & get it fixed.

Then get the Dell.... Sorry for the 560ti typo. Have fun!