$550ish LAN Build (before rebates) - Suggestions?

Try change the GPU to a GT as you are still under your budget. Believe me, the 512mb will definitely be useful.

Delete.

The 380w Earthwatts PSU that comes in that package should be fine. It has 27A on the 12V rails and would be fine for a mild OC on the e2180. Now I'd recommend getting a bigger PSU if your going to be doing some more extreme OC'ing or adding heavy power consuming GPU's to the equation. I have the same PSU/case combo running a e6700/x1800xt on it. I'd even bet that the 9800gtx would fit on my system and not stress the PSU too much. the x1800xt consumes about 101w and the 9800gtx is at about 110 watts. Now I'm not suggesting that you push your PSU hard, but I'm just stating that if you do some mild OC'ing on the e2180 and run the GPU at stock speeds you should be fine. The Antec Earthwatts series of PSU's are built well and have a 3 yr. warranty. There are other PSU manufacturers that build better PSU's, but they are more expensive. The Antec Earthwatts series PSU's are a nice blend of quality and price, IMHO.
The mobo you selected isn't the best, but for the $ it might work out. I'd rather spend a bit more and get something a bit better, but that is me. I'd rather ditch the TX2 cooler and just use the stock cooler, since you'll probably be limited on the CPU OC to about 2.6-2.8 gHz anyway. The $40 in savings could be used for a better mobo, which would allow you to OC to 2.8-3.2 gHz on the stock cooler. It's up to you, but that is where I'd put my $ for your build.

P.S. I'd buy the Gigabyte DS3L/Abit IP35-e/Asus p5k se series of mobo's. They are all around the $90 price range and sometimes drop below that with MIR's occasionally.