I've always liked storing IP's as binary(4) - still 4 bytes, but simpler conversions:

DECLARE @IpBin binary(4)

DECLARE @IpString varchar(15)

SET @IpString = '101.202.33.44'

--convert string to binary

SET @IpBin =CONVERT(binary(1), CONVERT(tinyint, PARSENAME(@IpString, 4)))

+ CONVERT(binary(1),...

IP's fit much better in binary(4) than bigint - the conversion is pretty simple and cuts down heavily on reads and index size