Of course I could buy 2 x 256 & sell my 2 x 128, but what a royal pain .. finding someone to buy my RAM, trying to get a decent price, packaging the stuff, paying shipping. Mushkin sells new rev 1.5 sticks for 
$89. Obviously, it'd be a whole lot easier (for me) to just call Mushkin, get my stick & pop it in - not to mention cheaper. 
My point is that the ability to use all 3 RAM slots is something worth considering. I know ppl who won't buy an 815e chipset cuz it's limited to 512MB RAM. If you know you're never gonna use more than 2 slots, then it doesn't matter, but I'd hate to decide somewhere down the road that I need that 3rd slot, and find out my board won't run when I fill the last slot. 
Rain, if u read the 815e round-up 
here at Anandtech (doesn't sound like u have), you'll see that they couldn't get *any* of the boards with 815e chipset to run stable at 133 with 3 RAM slots full .. except the CUSL2 - which is why they awarded it their 
Editor's Choice.
Here is where they said the MSI board wouldn't run at 133 w/ 3 RAM slots full. 
Maybe should give Mike a call & let him know how you got it to work, cuz he wasn't able.