How to re-install Vista with no CD ??? :(

Hello,

When I start my Dimension E520 i see the blue Dell logo and the BIOS does its part but then before I get to the Vista Login screen the screen goes black and all I can see is my white arrow cursor, and it just hangs there.

I have spoken to Tech Support who say I can either repair Vista or Re-install it - as this happened only this morning I have not had a chance to backup my data - How can I do this without being able to get onto the desktop.?

I was also advised to press F8 and select a repair or re-install option - but when I do this, I cannot see this option, apparently because I have had to re-install Vista once before.

So finally they suggested I use the VISTA DVD and re-install VISTA, however I never recieved any DVD's when I bought my PC (other than a Roxio one) and Dell are refusing to send me another.

What do I do ??  :(