is this DDR or SDRAM memory and is it the only memory you have.
is it possible to try this in someone elses computer, that may prove the memory is wrongly labled or not.
i have looked at the manual for your mobo and cant see any reason why it wont work UNLESS you have bought pc3200 ram (ddr 400mhz) which on your mobo should be reported correctly but would run at 333mhz due to that being the top speed your board can handle. might be why the memory is reported as half size...
IF you are using windows98 or ME then thats the reason for the incorrectly reported size, win98 + me support a maximum of 512mb (you can install more in seperate sticks but NOT a 1gig stick.