**EDIT**
I tried it at PC2100 speed and it works fine. With both sticks too. Strange that it benches about 100 points better at 266 than the original stick at 333. Do two sticks bench better than one stick ?
First Stick:
Xerox 512megPC2700 Samsung chips @ 333 = 1938 in SiSoft Sandra bench.
First stick with second stick:
Second Stick is a no name 512megPC2700 @ 266 with the first stick = 2068 in SiSoft Sandar bench.
I used aida32 to check the memory and both show as 512megPC2700 sticks set at PC2100 speed(266).