slack 12(32bit) mysql will use 8GB RAM

Hello Guys,
Have you experience using slackware 12 running mysql with 8gig memory? when i run mysqltuner it shows:
[OK] Currently running supported MySQL version 5.0.67
[!!] Switch to 64-bit OS - MySQL cannot currently use all of your RAM
[!!] Allocating > 2GB RAM on 32-bit systems can cause system instability
but my memory is 8GIG and i have enabled HIGHMEM so my top shows:
MemTotal: 8307436 kB
is there any way that i can maximize my mysql usage without upgrading to slackware 13 (supports 64 bit)? and without installing new OS?
Have you experience using slackware 12 running mysql with 8gig memory? when i run mysqltuner it shows:
[OK] Currently running supported MySQL version 5.0.67
[!!] Switch to 64-bit OS - MySQL cannot currently use all of your RAM
[!!] Allocating > 2GB RAM on 32-bit systems can cause system instability
but my memory is 8GIG and i have enabled HIGHMEM so my top shows:
MemTotal: 8307436 kB
is there any way that i can maximize my mysql usage without upgrading to slackware 13 (supports 64 bit)? and without installing new OS?