Get 2 GB (2x1GB) of Corsair Value. I've been perfectly happy with all the Corsair Value I've got. 1 GB Value in 'Gaming Rig' below concurrently with PQI TCCD 1 GB, and 512 MB in my old P4 PC. None of the Corsair Value memory sticks have ever been defective for me (nor has the PQI TCCD). The Value is just as fast as the TCCD chips at DDR400, at least within 5% only due to the timings. Right now I have a 4x512 configuration, but I recommend you go 2x1GB simply so you don't have to use 2T/DDR333. Not that 2T/DDR333 hardly makes a dent either though. You will have more slots left if you do 2x1GB.
The 7800GT is great. I have an eVGA 7800GT N515-AX, and I love it. 'AX' means great warranty I think. I picked mine up for $284 after rebate at newegg.
For the mobo, get an nForce4 one. Not sure which specifically is the best value at this point. I'm happy with my A8N-SLI Deluxe but it does have a couple problems.
The Seagate 250GB is an excellent value.
NEC DVD burner is fine, I love my HP dvd burner 420i too.
CPU (X2 3800+) is the best choice I've seen in the whole list, as good as the 7800GT.
As for LCDs, I'll recommend you those in my
LCD Buyer's Guide thread and continue discussion about them there.