Hi Miko,
The Microsoft.VisualBasic.Information namespace is not available to Windows Store apps.
Char.IsNumber will tell you if a given character is a number. In your case it doesn't look like this matters, since you're doing a direct string comparison: I'd just compare with the known character values without checking if it's numeric.
Alternately, use Integer.Parse() to convert the string to a number, but that may give you false positives for 0.
--Rob