Nero - Speed Measurement Question

Hey, Ive got a LiteOn 48125W, found some media that supported 48x and was hoping to burn at 48X. Went into to nero, allowed me to click on 48X to burn, but then when i use the “Determine speed” it ends up changing the burn speed to 40X cos the speed measurement ended up being 41.2X from both HD’s I have, I know that the measurement finds the lowest speed of access of the file, but i dont think it should be that low.

Here are my specs…just wanted to know what other people get in the speed measurement, and what i can do to fix it:

P3 800
DMA Enabled on all drives
IBM 20Gb 7200RPM ATA66 Pri Mas
Liteon 48125W Pri Slv
Quantum Fireball 20gb 7200RPM ATA100 Sec Mas
Pioneer 16X DVD Sec Slv

Put the Harddrives on IDE0 and the CDrom’s on the IDE1

the LiteOn as master on IDE1