BleepingComputer.com: Advice about viruses please?

Hi.
Can a virus enter a computer when it is switched off?
Can a virus be on a computer without the computer showing any signs of being infected?
If there were attachments to the virus eg pictures where would they go? (could they automatically go into ''received files'')
Could any attachments to a virus have the same layout in terms of properties, as pictures etc that have been accessed from elsewhere?

The computer in question has no internet safety at all, if that makes a difference.

One final thing, does anyone know ofa virus that went out at 23:30ish on Christmas Eve 08?

seem like random questions i know, but the answers are important, thankyou for you help.

hello
Can a virus enter a computer when it is switched off?
I would say no

Can a virus be on a computer without the computer showing any signs of being infected?
Yes. some such as rootkits.

If there were attachments to the virus eg pictures where would they go?
Probably anywhere.

Could any attachments to a virus have the same layout in terms of properties.
Not sure exactly what you mean by properties,but they can disguise themselves as legitimate files,drivers,services etc..

The computer in question has no internet safety at all, if that makes a difference. This makes the biggest difference..
It can take only minutes for a computer to be infected over the internet. Of course if it is never connected it reduces that chance. It's sort of technical suicide to access today's web unprotected.

One final thing, does anyone know of a virus that went out at 23:30ish on Christmas Eve 08?
couldn't say for sure if a specific virus.

Would you like a scanner to run??

There wouldn't be much use in that as this computer isn't the one in question.
Thankyou for your help.
xxxx