thanks ilikefree, then its a good idea once in a while to plug the external hardrive in and do a system restore,it might help the situation like mine where the external hardrive was wiped clean patch41
It is a good idea to include your external hard drives in your all of your back-ups. For that reason, I've given all of my external drives, individual drive identification letters [F:, G:, K:, M:, etc.] which helps for instant recognition.
I also suggest that you also include them in any Anti-virus, Malware and Spyware scans from time to time - that way it helps to keep everything clean. I 'hit' mine with checks by Malwarebytes' Anti-Malware, Spybot S&D, and SUPERAntiSpyware Free Edition, from time to time.
Another recommendation is to also include the external hard drives in your defragmenting admin. I use AusLogics [free] - again, every now and then. I've found AusLogics to be extremely reliable and far quicker than the installed Vista system defrag.
A word about Acronis - I too had it, but found it to be rather cumbersome, unreliable, slow and just downright frustrating. I've since tossed it out and use instead Macrium Reflect [free] from Paramount Software UK. It is a very simple bit of software to use, and easy to navigate around. Very reliable as well.....for example just yesterday, I did 185Gb total of back-ups of 4 system partitions, and 2 external hard drives, to another external hard drive; time taken = 1 hour 20 minutes.
All free software listed above, have links available from Brink's excellent guide; Free Software List for Vista - Vista Forums, here;
http://www.vistax64.com/software/115872-free-software-list-vista.html
Hope all this helps.