In general removing any greetings before the question is a good idea because it cuts into what people see on the Questions page.
Removing the thanks isn't at the end isn't as important but if you are editing I would remove it for brevity's sake.
Jon Skeet recently wrote about Asking the Perfect Question which talks about not including Hi/Thanks questions. He said specifically
There's no need to include greetings
and sign-offs such as "Hi everyone!"
and "Thanks - hope to get an answer
soon" in the question. These will
often be edited out by other users, as
they're basically a distraction.
Greetings at the start of a question
are particularly useless as they can
take up valuable space in the snippet
displayed in the question list.
Which to me means we need to edit these things out when we can.