It is possible to enable VT
I bought a VGN FE-41Z in early 2007. It had the same issue - BIOS set-up has no facility to enable VT on the Intel Core 2 Duo CPU. I bought it for the virtualization functionality. I use Linux rather than Windows and use KVM extensively.
I investigated the Phoenix BIOS and discovered that by changing a bit flag in the NVRAM settings VT can be enabled since the BIOS code that enables VT *does* check the flag. It is just that Sony don't provide a menu option for it and the default state is disabled. Each setting in NVRAM is called a Token and each has a number.
Using the Phoenix symcmos.exe utility with FreeDos on a bootable CD the token can be changed in NVRAM.
From May 2007 the FE41Z has had VT enabled and I've never had to mess with the flag again.
I posted my findings and several other people were able to enable the VT on their Vaios too.
Unfortunately there isn't a universal foolproof method of determining which NVRAM token to change - each model is different (based on the options built into each BIOS image).
The key is to extract the BIOS image into its constituent modules and then find the code that checks the token and sets the CPU flags (usually in BIOSCOD6.rom).
The code will look something like this (my comments added):
0000A855 0FA2 cpuid
0000A857 25FF0F and ax,0xfff
0000A85A 3DE106 cmp ax,0x6e1
0000A85D 722E jc 0xa88d
0000A85F 660FBAE105 bt ecx,0x5
0000A864 7327 jnc 0xa88d
0000A866 66B93A000000 mov ecx,0x3a ; MSR VMX control
0000A86C 0F32 rdmsr
0000A86E 660FBAE000 bt eax,0x0
0000A873 7218 jc 0xa88d
0000A875 50 push ax
0000A876 B89501 mov ax,0x0195
0000A879 9A204100F0 call 0xf000:0x4120
0000A87E 58 pop ax
0000A87F 7405 jz 0xa886 ; ZF set == VMX disabled
0000A881 660FBAE802 bts eax,0x2 ; Enable VMX
0000A886 660FBAE800 bts eax,0x0 ; Lock MSR until power cycle
0000A88B 0F30 wrmsr
Locate this code by finding the instructions:
66B93A000000 mov ecx,0x3a
The code following is likely to be the setting code, but needs confirming. There can be other reads of this MSR.
The Token number is then seen in the AX register when calling the BIOS's Read NVRAM token sub-routine:
In this case the Token is 0x0195
Use symcmos.exe to save the text file containing all the tokens and their values:
A:\ symcmos.exe -Lliteral.txt
( SYMBOLIC CMOS EDITOR - Version 643710-032 )
( BIOS Version: NAPA0001.86C.0032.D.0702051952 )
CRC = 2786
Edit the text file, change the token you've identified from 0000 to 0001, save the file, then use symcmos to rewrite the settings into NVRAM
Restart and if you've done it correctly VT is enabled.