I'm not sure exactly how the OS maps vxd sections, I think it's dependant on load order, size of the sections, available memory, etc., and not to any inherent reloc info. as might exist in PE files. I haven't got things installed any longer to look into it further.
The easiest thing to do is get the "real" starting address of the driver sections with the 'VXD' command and calculate the offset from the disassembled addresses as seen in IDA. You can then use this raw->virtual offset to unassemble selected instructions and read the real Data variable addresses from the Softice window.
If you were really interested, you could look into how the Vxd_Desc_Block DDB structure was initialized when a driver is loaded, along with the Device_Location_List, ObjectLocation and other structures which define linear address and other info about a driver. But methinks this is not the case
