To Hyperthread or Not to Hyperthread

this may not be the best place to put this question because it's a HOST issue. but perhaps there's somebody out there who knows how to fix this:

I want to create a linux based VMware Server host. I have a P4 machine and installed Centos 4.4 on it. In the bios i have ACPI enabled and when i boot the SMP kernel, i cat /proc/cpuinfo and see this:

processor       : 0

vendor_id       : GenuineIntel

cpu family      : 15

model           : 4

model name      : Intel(R) Pentium(R) 4 CPU 2.80GHz

stepping        : 1

cpu MHz         : 2795.449

cache size      : 1024 KB

fdiv_bug        : no

hlt_bug         : no

f00f_bug        : no

coma_bug        : no

fpu             : yes

fpu_exception   : yes

cpuid level     : 5

wp              : yes

flags           : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe pni monitor ds_cpl cid xtpr

bogomips        : 5590.25

that tells me (the 'ht' flag) that hyper threading is possible. but if hyper threading is indeed enabled, i should see 2 processors in cpuinfo. i tried adding 'ht' or 'acpismp=force' in the boot string of the smpkernel but nothing seems to bring hyper threading to life.

since this is a single CPU machine and i run some 5 generally low-load VMs on it, i'd really like to have hyper threading available. does anybody know how????