WinDbg is a great tool if You know how to use it. There could be a lot of caveats, like the one in the subject line.

0:000> .loadby sos clr
0:000> !threads
SOS does not support the current target architecture.

If You create a 32bit dump on a 64bit machine via taskmanager dont forget to use the appropriate taskmgr.exe! You should use C:\Windows\SysWOW64\taskmgr.exe instead of the 64bit one executed by Ctrl-Alt-Del menu or other means. Otherwise the dump may be unusable.