How to obtain a variable Server Account Name using an @SQl with an @variable_server_ name + 'master.dbo.xp.instance.regread ...'

Question

Hi,
I am trying to make a flexible script to get the Service Account Name from several servers.
I am using "servername.master.dbo.xp_instance_regread.......", but I want to use a variable for the servername.
So I started doing this:
Declare @servername varchar(100)
Declare @SQL varchar(1000)
Declare @agtServAccName varchar(250)
set @servername = 'Server1'
set @sql = @servername + '.master.dbo.xp_instance_regread
N''HKEY_LOCAL_MACHINE'',
N""SYSTEM\CurrentControlSet\Services\SQLSERVERAGENT'',
N''ObjectName'',
@AgtServAccName Output,
N''no_output'''
Execute (@SQL) 
How am I able to get a flexible script (@sql), which gives me the Service Account Name of the server called @servername after I execute this script (@sql)
If there is another way without this regread, I like to hear that too ofcourse...
EDIT: the reason I use a variable for the servicename is, that I am running it on a central management server and not on the server with this servername itself.

Answer 1

This did the trick. Now I can loop through all my centrally managed servers and obtain the Service Account Names.
Thanks for the help. There's probably a better way to do it (sp_executesql?) , but at least I got something.
Declare @ServerName varchar(50)
Declare @SQL as varchar(500)
If object_id('tempdb..#ServAccName') is not null
drop table #ServAccName;
create table #ServAccName (ServAccName varchar(50))
set @ServerName = 'Server1'
set @SQL = '
declare @ServAccName varchar(50)
  execute ' + @ServerName + '.master.dbo.xp_instance_regread
                   HKEY_LOCAL_MACHINE,
                   ''SYSTEM\CurrentControlSet\Services\MSSQLServer'',
                  ObjectName,
                  @ServAccName OUTPUT
Insert #ServAccName Select @ServAccName
Exec (@SQL)
Select ServAccName from #ServAccName