You can do the conversions on the fly in a single query by using expressions in your joins and where clauses. It may be slower than joins using the same datatypes, but definitely faster than doing it by hand.
declare @table1 table ( value1 varchar(50) )
insert into @table1 select 'D19377322B06194DB6A9B34667D506A6'
declare @table2 table ( value2 binary(50), value3 nvarchar(50))
insert into @table2 select convert(binary,'0xD19377322B06194DB6A9B34667D506A6'), '{E867D837-EB0C-4EDB-B56E-D7083C181E52}'
declare @table3 table ( value4 uniqueIdentifier)
insert into @table3 select 'E867D837-EB0C-4EDB-B56E-D7083C181E52'
select value1,value2,value3,value4
from @table1 t1
join @table2 t2 on t2.value2 = convert(binary,'0x'+t1.value1)
join @table3 t3 on t3.value4 = substring(t2.value3,2, len(t2.value3)-2)
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