I had the same proble on my daughter's laptop NB200xx.
But the Zero trick did crash, in fact I was stuck on the setup screen or a black blinking one.
No ext CD/DVD, no recovery disk. I used another computer to make a booteable USB key with AVG rescue cd (from an ISO of the CD)
Then I booted on the USB key (the F12 key did call the boot menu, hopefully)
From there I discovered 2 virus on the 2 main partitions, one on a system file. I deleted all but the system file (may be I should have, dont know).
Then after trying to see wich partition was correct I discovered that the recovery partition was, in the file utilities from AVG I declared the recovery partition bootable, start again the NB 200 , and voila, it installed me a frew window version, without harm to the "data" partition.
Indeed I should have secured the/users/document content on the USB key before, but I am yet happy with the result.
Strangely I have not seen that method documented anywhere..
If someone have something to add I'll be pleased to read that.
Best regards - ISaac