Welcome Marsels, in case you're still confused, the TPB breakdown goes like this:
Ultimate Spider-Man Vol 1 (#1-7)
Ultimate Spider-Man Vol 2 (#8-13)
Ultimate Spider-Man Vol 3 (#14-21)
Ultimate Spider-Man Vol 4 (#22-27)
Ultimate Spider-Man Vol 5 (#28-32)
Ultimate Spider-Man Vol 6 (#33-39)
Ultimate Spider-Man Vol 7 (#40-45)
Ultimate Spider-Man Vol 8 (#47-53)
Ultimate Spider-Man Vol 9 (#46, Ultimate Six #1-7)
Ultimate Spider-Man Vol 10 (#54-59)
Ultimate Spider-Man Vol 11 (#60-65)
Ultimate Spider-Man Vol 12 (#66-71)
Ultimate Spider-Man Vol 13 (#72-78) *this isn't out yet but should be soon*
Ultimate X-Men Vol 1 (#1-6)
Ultimate X-Men Vol 2 (#7-12)
Ultimate X-Men Vol 3 (#13-20)
Ultimate X-Men Vol 4 (#21-25)
Ultimate X-Men Vol 5 (Ultimate War #1-4)
Ultimate X-Men Vol 6 (#26-33)
Ultimate X-Men Vol 7 (#34-39)
Ultimate X-Men Vol 8 (#40-45)
Ultimate X-Men Vol 9 (#46-49)
Ultimate X-Men Vol 10 (#50-53)
Ultimate X-Men Vol 11 (#54-57) *this isn't out yet but should be soon*
The Ultimates Vol 1 (#1-6)
The Ultimates Vol 2 (#7-13)
The Ultimates 2 Vol 1 (#1-6) *this isn't out yet but should be soon*
The Ultimates 2 Vol 2 (#7-12) *this isn't out yet but should be early 2006*
Ultimate Fantastic Four Vol 1 (#1-6)
Ultimate Fantastic Four Vol 2 (#7-12)
Ultimate Fantastic Four Vol 3 (#13-18) *this isn't out yet but should be soon*
Ultimate Marvel Team Up Vol 1 (#1-5)
Ultimate Marvel Team Up Vol 2 (#9-13)
Ultimate Marvel Team Up Vol 3 (#14-16, Ultimate Spider-Man Super Special #1)
*With the UMTU series, your best bet is to pick up the Hardcover, as it includes all 16 issues plus the USM Super Special #1. For some reason the softcover TPBs skipped #6-8, which coincidentally were the best in the whole run.
Ultimate Galactus Vol 1 (Ultimate Nightmare #1-5)
Ultimate Galactus Vol 2 (Ultimate Secret #1-4) *this isn't out yet but should be soon*
Ultimate Adventures (#1-6)
The Hardcovers are basically like two softcovers combined. So whereas the first thirteen issues of USM were collected in the two separate volumes, by buying the hardcover you get all 13 in the one package:
Ultimate Spider-Man Hardcover Vol 1 (#1-13)
This is true for most of the titles, though Ultimate Adventures, since it was only 6 issues, will probably never come out in HC (we're lucky it came out in softcover).
Hope that helps. And if you're ever wondering how the stories take place in relatation to each other, check out the Ultimate Marvel Timeline, its been up here on UC.com for over a year now and I update every Wednesday a new Ultimate title ships:
http://www.ultimatecentral.com/forum/showthread.php?t=3293&page=1