Okay so this is old info and could be BS, but good fun to speculate.
According to www.chartsinfrance.net here are the highest selling artists worldwide with album sales only! In millions.
I deleted all the non-pin related bands I know of. Note that some of these bands have put out several albums since the stats were compiled, but I wouldn't imagine the sales are big enough to jump the band above them on the list except maybe the Rolling Stones, and there's Guns n Roses who technically could be considered the same band.
1 - Beatles = 346.500.000 (12/2007)
5 - Elvis Presley = 187.000.000
6 - Elton John = 177.200.000 (01/2008)
8 - Rolling Stones = 169.100.000
10 - Led Zeppelin = 165.500.000 (01/2008)
17 - AC/DC = 133.700.000 (11/2007)
34 - Metallica - 102.500.000 (01/2008)
39 - Guns N' Roses = 93.200.000 (12/2007)
72 - Iron Maiden = 59.700.000 (02/2008)
84 - Kiss = 54.500.000 (11/2008)
This wiki article shows some different numbers.
http://en.m.wikipedia.org/wiki/List_of_best-selling_music_artists