SC1430 / ESX 64-bit guest support

I recently got a SC1430 with dual E5310 procs but it seems like ESX 3.5 doesn't recognize Intel VT support. Granted, this server is not on VMware's HCL, but I'm still hoping somebody may have some advice. VT support is enabled in the BIOS, booting off a CPUID disk shows VT support enabled for all procs, and CentOS 5 64-bit will install without problems. /proc/cpuinfo under ESX doesn't show vmx support though. I'm scratching my head trying to figure out what may be going on. Anybody have any advice?