What is processor upgrade limit for gateway ml6230

http://support.gateway.com/s/Mobile/2007/Oasis/4006174R...

Supported: Intel® Merom, Yonah Dual-Core/Single Core and Celeron-M CPUs
Package: 479-pin, uFCPGA
FSB: 533/667 MHz

I think some select intel core solos and some petnium duos? Depends on if gateway made their motherboard support other cpus though. No guarantees...

i guess what i really want to know is which is the highest ghz i can use

It's a laptop and laptop CPU upgrades are difficult.
Here's another thread about it:
http://archive.slickdeals.net/showthread.php?t=747613

Probably the fasted CPU you can stick in is a T2700 (dual core, 2.3GHz). You can buy a T2600 (2.16 Ghz) for like $40 on Ebay and $60 in a few online stores. The T2X00 CPUs are your ONLY options.