I am sorry I did not get here sooner, the first thing I thought as soon as I started reading was the K7N2 Delta mem compatibility problem.
I, like you, had atleast one all nighter trying to root out the problem until i finally came ot the Nvidia compatibility chart.
The stick I had were corsair and they would only boot 40% of the time.
Anyway, I replaced them with 2 sticks of Samsung original 512 PC2700, which was on the compatibility list, and no probs, i have now replaced those with 2 sticks of 512Mb Twinmoss w/winbond PC3200, which is on the compatibility list, and no probs.
I have just built a second system for a friend with the K7N2G-L (i actually have the K7N2-ILSR my self) and used 2 sticks of crucial 256 PC2700, works fine, even though no crucial ram appear to have been tested for the compatibility list.
I did find these crucial sticks on the MSI forum's patched togethor list of approved mem modules that work though, it is very useful, see here:
http://forum.msi.com.tw/thread.php?threadid=14555&sid=
I am actually running an Xp2500+ Barton running at 2.2Ghz, identified as an XP 3200+, with the K7N2 Delta - ILSR, and the 2 sticks of 512mb PC3200 Twinmoss with winbond chips (Dual channel)
Very similar to your system, so it should be ok with the right Ram.
Good luck with it
, i would only recommend approved Ram though ! The MSI forums ram list is a good enough reference though, as the nvidia compatibility list is very limited.