text-based triggers

Hi everyone, I'd be grateful for any advice :-)

I have no experience with macros or VB (except from playing around for two days and reading these forums), but I'm attempting to make a template which will autofill various details on a form when a certain word is written in a cell. I've recorded the macro, but I need to find a way to trigger it when the text (in this example "IGEN") is typed. Is this possible (I've read about using a hot key, but I want the macro to run when the text is entered, so that I can have several optional words that could be entered).

Also, this code only works when IGEN is written in cell C8... how can I make it work for any row in column C, such that macro auto enters details into cells dependant on the reference of the initial cell. If that makes any sense? :-)

Also, if I'm using several different 'key' words, each triggering a different set of details to be autofilled, do these all have to be on different macros, or subs??

Here's my code so far. Many thanks in advance for your time.
SteveT

Sub IGEN()
'
' IGEN Macro
' Macro recorded 16/03/2005 by joule Autofill details for IGEN
'
If Range("C8") = "IGEN" Then
Range("D8").Select
ActiveCell.FormulaR1C1 = "IGEN"
Range("E8").Select
ActiveCell.FormulaR1C1 = "1"
Range("F8").Select
ActiveCell.FormulaR1C1 = "<-60°C"
Range("G8").Select
ActiveCell.FormulaR1C1 = "Kathryn Bates, QC UK"
Else
ActiveCell.Offset(1, 0).Select
End If

End Sub