Hope this video will help - http://www.youtube.com/watch?v=BaYxwKUnw0U
It shows, step by step, how to create Excel file with multiple sheets

I had similar problem a few years ago and found a solution (quite complicated) which I placed here: [URL="http://vbdotnettutorial.blogspot.com/2006/05/access-to-path-is-denied.html"]http://vbdotnettutorial.blogspot.com/2006/05/access-to-path-is-denied.html[/URL]
I know it is hard to read, but maybe will help a little.

[QUOTE=ssommaro;1106099]If you store your number in a variable of decimal type, you can convert into a string with two decimal places (including .00) this way:

Dim dAmount as Decimal
Dim strFormattedAmount as String

strFormattedAmount= dAmount.ToString("N2")[/QUOTE]

Try this:
String.Format("{0:f2}", CType("10.22222222", Decimal))