The most likely thing that's infected with a virus is the un-authorized (stolen) copies of Windows XP you're using.
If you suspect the BIOS, why not update it? The page for that Acer Aspire X3200 shows versions R01-A4 and R01.B0 available. Haven't read the manual, but most have the ability to update the BIOS without an OS.
Also as mentioned above, you may "need" to re-partition the hard drive manually - use a boot diskette and run the utility from the drive mfg. Or plug the drives in as secondaries to a working system, remove the partitions and reformat. The acer drive is likely to have had a non-DOS partition to hold the OS it was shipped with.