Two questions about computers.

[Mystic Muse]

Say I were to install both Ubuntu and windows on a computer. If I were to visit a site that gives viruses to windows on the Linux OS, would it then proceed to affect the windows one even though I was using Linux? The OS in question is Ubuntu 8.10 if that matters at all.

Also, I have a site I sometimes go to for modifications to a game (Fable the lost chapters).This http://fabletlcmod.com/forum/ is the site I go to. I haven't used the mods as I don't have a computer I can risk it on. Does anybody know if these mods would give viruses to a windows machine? Specifically windows seven.

I imagine the first question is rather obvious but I know hardly anything about computers so I thought I should ask.

[Manga Shoggoth]

The answer is that it depends on how you are running things.

Very briefly, most viruses are tied to a single platform, be it Windows, Unix or something higher-level like Word (macro viruses). Thus, a windows virus shouldn't affect the unix side of things...

...except...

If the infected subsystem can access the files on the "clean" subsystem (if, for example, you have a unix disk mounted in windows or vice versa), then the virus can corrupt those files. Technically, the virus hasn't infected the other subsystem (as the virus won't run in the other subsystem) but you will still have the damage to deal with.

Also there are tunnelling effects. For example, you can download an infected windows file in unix. The file won't affect unix, but will affect windows if run in windows.

[BisectedBrioche]

1. Since both OSs wouldn't be running at the same time you would have to infect them separately. There's also a fairly good chance a virus written to infect one won't be compatible with the other (especially if it it relies on some flaw in the security of one OS). System incompatibility has it's upsides sometimes.

2. As a virus is a program like any other you'd need to run an it to make it do anything. Since mods tend to be extra data for an existing application to use, this seems unlikely (although a mod could have a virus hidden within it, it would probably show up). If the community is reputable (i.e. it's not full of people who'd want to try and sneak a virus onto your computer for no reason) then you're probably OK.

[The Succubus]

Hmmm. If it's a virus that affects the bootloader it could be problematic.