CHIP LOWEST PW PRICE AVG. OVERCLOCK (per overclockers.com)
1ghz duron $39 1203
1ghz athlon $78 1344
1.2 ghz athlon $78 1416
1.3 ghz athlon $86 1514
1.4 ghz athlon $86 1609
Given the price differentials, it seems like the only options that make sense are the 1.4GHz Athlon or the 1GHz Duron. All the other Athlons you list have lower performance for the same $ or only slight less $.
Since your motherboard only accepts SDRAM, I wonder if the performance difference between the Duron and the Athlon is that great with the motherboard.
This article compares the performance of a 1GHz Athlon in the KT7-RAID with a Duron 700MHz in the KT7-RAID. It concludes that the Athlon is theoretically about 34% faster under the conditions tested, but that in "real-world" gaming tests it was only about 4.3% faster. The latter result is skewed, however, due to a fill-rate-limited GEForce DDR video card. With your GEForce 2 video card, you might realize some of that 34% performance differential, so the real question for you seems to be whether you want to spend $47 for something that might be around a 34% performance increase.