Delphi Detect Word version through Registry - delphi

Question

I just added this function which determines which mailmerge method to use. It seems to work on XP and Windows 2000. Is there any reason why it wouldn't work on NT, Vista, 7 and other Windows versions? I'm thinking will there be an issue with the registry?
function GetMSOfficeVersion: String;
var Reg: TRegistry;
begin
Result := 'Office Version Not Found';
// create the registry object
Reg := TRegistry.Create;
try
// set the root key
Reg.RootKey := HKEY_LOCAL_MACHINE;
// check for Office97
if Reg.OpenKey('\SOFTWARE\Microsoft\Office\8.0', False) then
begin
Result := 'Microsoft Office97';
end;
// check for Office2000
if Reg.OpenKey('\SOFTWARE\Microsoft\Office\9.0', False) then
begin
Result := 'Microsoft Office2000';
end;
// check for OfficeXP -- not sure if this is correct
// you have to verify the key on a machine with OfficeXP
if Reg.OpenKey('\SOFTWARE\Microsoft\Office\10.0', False) then
begin
Result := 'Microsoft OfficeXP(regkey10)';
end;
// check for 11.0
if Reg.OpenKey('\SOFTWARE\Microsoft\Office\11.0', False) then
begin
Result := 'Microsoft OfficeXP(regkey11)';
end;
// check for 12
if Reg.OpenKey('\SOFTWARE\Microsoft\Office\12.0', False) then
begin
Result := 'Microsoft Office2010';
end;
finally
// make sure we free the object we created
Reg.Free;
end;
end;

Answer 1

Probably insufficient privileges. Try using OpenKeyReadOnly instead of OpenKey.

Answer 2

Aside from making sure you create the registry in read-only mode, like TOndrej suggests, you'll also want to fix the version matching in that code, as it is wrong.
Here are the right numbers for the parts where things gets shady in your code fragment:
10.0 = Office XP
11.0 = Office 2003
12.0 = Office 2007
13.0 - doesn't exist, obvious Microsoft/US numbering standards.
14.0 = Office 2010

Answer 3

"Is there any reason why it wouldn't work"
Yes, individual products may create a Software\Office\#.0 entry, you should be checking for a Word subkey in the specific version's key. Even then, f.i. 'Word Viewer' might have created the Word subkey which wouldn't do mail merge. If you really want to go with the registry better look for Word.Application keys in HKEY_CLASSES_ROOT. Apart from Word.Application.# keys the Word.Application key itself has a CurVer subkey.
(Previously I suggested the below but Fox's comment to the question is much better I think.)
I would directly try to create the automation object, if it fails then that version is not available, fallback to a lower version. Or sth. like:
function IsWord14: Boolean;
begin
Result := True;
try
CreateOleObject('Word.Application.14');
except on E:EOleSysError do
if E.ErrorCode = HRESULT($800401F3) then // invalid class string
Result := False
else
raise;
end;
end;