It looks to me like there are 2 separate downloads/CDs etc for 32 Bit & 64 Bit
Microsoft SQL Server Standard Edition 2005 32 Bit CD/DVD 5 Client (Windows)
2 new from $1,800.00
Microsoft SQL Server Standard Edition 2005 64 Bit CD/DVD 1 Processor License (Windows)
2 new from $3,500.00