WPF: Expression Studio 4 Ultimate and VS V10

Question

I want to thank those who have helped coax me over the line to WPF instead of Forms programming.  I really appreciate the help I've received here.
Now, before I spend my limited funds on Expression Studio 4 Ultimate, are there any alternatives that are "Better " for WPF development than Expression Studio 4 Ultimate?
I can get ES4U for a good price, but I'm wondering if there is a better application out there, even for a little more money that will do a better job.
Note: I am currently using Visual Studio V8 Pro... Is there really any advantage to upgrading to V10 Pro or would you just stick with V8?
Thanks in advance for everyone's feedback and I really hope I can be of help to others sometime in the future like I've received here.