Well, since you've posted the top 10 i may as well post the full top 50 with sales...not that, IMO, it means as much as it should as these figures DO NOT include back catalogue sales (that's sales from all albums released in the 20th century), greatest hits, live albums or downloads...so just sales of Studio Albums released from Jan 1st 2000 to Oct 11th 2005 :
1 ROBBIE WILLIAMS 6.3 m(illion's)
2 COLDPLAY 6.2 m
3 DIDO 5.7 m
4 EMINEM 4.7 m
5 WESTLIFE 4.2 m
6 NORAH JONES 3.3 m
7 BLUE 3.3 m
8 ANASTACIA 3.1 m
9 STEREOPHONICS 2.8 m
10 OASIS 2.6 m
11 KYLIE MINOGUE 2.6 m
12 PINK 2.5 m
13 CRAIG DAVID 2.4 m
14 WILL YOUNG 2.4 m
15 SCISSOR SISTERS 2.3 m
16 KEANE 2.3 m
17 RONAN KEATING 2.3 m
18 U2 2.3 m (1.11 m for ATYCLB + 1.19 m for HTDAAB)
19 AVRIL LAVIGNE 2.2 m
20 S CLUB 2.2 m
21 BUSTED 2.2 m
22 RUSSELL WATSON 1.9 m
23 RED HOT CHILI PEPPERS 1.9 m
24 MADONNA 1.9 m
25 SUGABABES 1.9 m
26 KATIE MELUA 1.9 m
27 BRITNEY SPEARS 1.8 m
28 DANIEL BEDINGFIELD 1.8 m
29 LINKIN PARK 1.8 m
30 ATOMIC KITTEN 1.8 m
31 JOSS STONE 1.8 m
32 MAROON 5 1.8 m
33 CHRISTINA AGUILERA 1.8 m
34 JUSTIN TIMBERLAKE 1.8 m
35 GREEN DAY 1.8 m
36 BLACK EYED PEAS 1.7 m
37 ENRIQUE IGLESIAS 1.7 m
38 ROD STEWART 1.7 m
39 DESTINY'S CHILD 1.6 m
40 50 CENT 1.5 m
41 ALICIA KEYS 1.5 m
42 DANIEL O'DONNELL 1.5 m
43 STREETS 1.5 m
44 NELLY 1.5 m
45 TRAVIS 1.5 m
46 WHITE STRIPES 1.4 m
47 DARKNESS 1.4 m
48 JOOLS HOLLAND 1.4 m
49 NICKELBACK 1.3 m
50 IL DIVO 1.3 m