Quick & Dirty way to update “IDs” in a string formatted as XML (C#)

<VAR NAME="sf_name" ID="1001210">

ID="(d+)"

Regex r = new Regex("ID="(\d+)"");
string outputXml = r.Replace(inputXml, new MatchEvaluator(ReplaceFunction));

public string ReplaceFunction(Match m)
{
  // do stuff with m.Groups(1);
  return result.ToString();
}