Cameron County is impractically far for me (mabey not for you) as I'm just
off of US209 just below where it crosses from Monroe into Carbon County.
Back to the computer, do you have two physical hard drives each with a
seperate operating system installation on it OR do you have a single hard drive with two partitions each with an OS installed?
The Dell 1721 does have a second drive bay so two physical drives IS possible.
As for how a virus can "migrate" from two seperate drives to infect both operating systems that's easy, if you have a multi-boot setup you have ONE Boot loader.
a virus on one drive can infect the boot loader and that can infect the other drive.
I generally don't like multi boot setups for that reason I may set up more than one OS for a computer, but I'll switch by shutting down and physically moving data & power cables.
If both of your drives are "infected" even data recovery is "risky" and at this point I'd suggest a clean sweep and start over.
I've crossed paths with a few vary nasty worms that persisted even past a format and reinstall, so when I encounter a known virus these days I use a scorched earth policy.
I clone another drive over the infected drive and even clone over the bootloader, this kills EVERYTHING.
Of course I have a full set of XP, Vista and Windows 7 Dell reinstallers
which makes it all easier for me to start over.
there is no replacing physical media