Ive agreed to build someone a website, someone else is doing the design, graphics and copy, im just doing the code.

Its been a dammed long time since I've built a site so I dont know what I should be coding it in.

Im a C# .NET developer day to day so .NET technologies will be easier to pick up. So should I be using:

ASP.NET
Silverlight
HTTP/CSS/PHP/Javascript combo like the good old days
HTML5 - is anyone using it yet?
Something else Ive missed?

The site should be pretty simple, doesn't need any Web2.0 features or data back-end as far as I know (full spec. not yet confirmed).

Anyone who has a clue, input would be appreciated.

If it has no special functionality requirements just setup a Wordpress backend and roll with standard PHP/HTML/Javascript, customising/creating a Wordpress theme. If it's not going to be a big site at all or require any kind of backend then you might as well use Dreamweaver dare I say it. If you want to brush up your skills fire up Notepad/Textpad and draw it up by hand in HTML/CSS

HTML5 is just a few neat multimedia extensions to HTML, not actually a new HTML language (for most sites you'll see its being used for displaying video at the moment using the <canvas> tag)

ASP is dead, forget Silverlight or anything else like that.

French.