If you set it up as a table, you can do what I think you're asking. If you get a third image, simply after the [ /td ] and before the [ /tr ] insert a [ td ] (stuff goes here) [ /td ]. (minus the spaces)
I can't explain to you exactly what they do because anything I learned about HTML went out the window, but TR controls the vertical stacking of boxes, where TD controls the horizontal stacking.
Just Copy+paste what's in the code box into your sig.
IGN: ~Trung4444~ 90/4x/50 Sinx [ + ]Trung[ + ] 99/50 Priest ~Trung4~ 99/50 Sin .Trung. 9x/6x LK -Trung- 99/50 Knight
|  |
[table][tr][td]IGN: ~Trung4444~ 90/4x/50 Sinx [ + ]Trung[ + ] 99/50 Priest
~Trung4~ 99/50 Sin .Trung. 9x/6x LK
-Trung- 99/50 Knight
[img]http://i53.tinypic.com/18p3c7.jpg[/img][/td][td][img]http://i53.tinypic.com/2ppjvrk.png[/img][/td][/tr][/table]Another option:
IGN: ~Trung4444~ 90/4x/50 Sinx [ + ]Trung[ + ] 99/50 Priest ~Trung4~ 99/50 Sin .Trung. 9x/6x LK -Trung- 99/50 Knight |  |  |
[table][tr][td]IGN:
~Trung4444~ 90/4x/50 Sinx
[ + ]Trung[ + ] 99/50 Priest
~Trung4~ 99/50 Sin
.Trung. 9x/6x LK
-Trung- 99/50 Knight[/td]
[td][img]http://i53.tinypic.com/18p3c7.jpg[/img][/td][td][img]http://i53.tinypic.com/2ppjvrk.png[/img][/td][/tr][/table]