FreeBSD 6 on a Compaq DL360

[Tom]

I'm installing pfSense (which uses FreeBSD 6) on a Compaq DL360 (p21).
 This is the 1st gen on the machine with 2 800 MHz CPUs.

During the boot process, it hangs at "SMP: AP CPU #1 Launched!".
After a few minutes wait it resumes.

If I boot with "Boot FreeBSD with ACPI disabled" it seems to work
fine. (no lag at boot)

I've tried setting the machine type to NT4, Linux and SCO UnixWare 2.1
using the SmartStart CD as suggested while searching Google, but they
all cause the machine to hang at the same spot.

Are there any issues with running with ACPI disabled?
If not, what is the proper way to permanently disable it?

thanks.