Newbie Needs Help With A Complex Query

I am new to SQL but I have jumped into it fairly deep. I need to write a query to generate a report that counts systems by the first two characters in the system name and gives a count by the first two characters and a total of all the systems.
The first part I have but I cannot think of how to get an overall total.
Here is the code I am using:
select
substring(dm.[Name],1,2) as 'Location',
count(distinct dm.[Name]) as '# Discovered',
count(distinct w.[Name]) as '# Managed',
count(distinct w.[Name])*100 / count(distinct dm.[Name]) as '% Managed'
from DiscoveredMachines dm, Wrksta w

where datediff(dd,dm.[DiscoveryDate],getdate()) < 90
and dm.[Name] *= w.[Name]
and (dm.[Name] like 'AB%' or dm.[Name]like 'CD%' or dm.[Name] like 'AD%'
or dm.[Name]like 'CB%' or dm.[Name] like 'SX%'
or dm.[Name] like 'EX%')


group by substring(dm.[Name],1,2)

compute sum(count(distinct dm.[Name])),
sum(count(distinct w.[Name]))


The results look like:
Location # Discovered # Managed % Managed
AB 30 27 90
AD 15 15 100
CB 20 19 95
CD 20 20 100
EX 35 30 86
SX 10 9 90

And then a separate result group with

sum sum
130 120

Is there any way I can get the sum on the same result group?
AM I even making sense?