Being 'unsupported' just means that Canonical won't roll out updates for that version, and so (IIRC) updates for intrepid won't be in the ubuntu.com archives anymore. But you should be safe, though you'll miss critical updates, if any. Which (IMHO) is not a problem, as Linux in general is fairly secure anyway. (I have a copy of Damn Small Linux from 2008 which is still safe) If you're really worried, get a CD from someone :D
Chris' answer is correct. You should worry if you were running a network server, but for a desktop is not such a big deal if you follow some security best practices like running only the necessary services and using a firewall.
Notice that you'll have problem to install new software as official repos will be eventually discontinued. You may evaluate upgrading to Ubuntu 10.04.01 LTS, as LTS versions have a wider span of support
Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly
to your computer or smartphone by using a feed reader.