What you need is a webservice to spell check. There is one at
http://ws.cdyne.com/SpellChecker/check.asmx, which you can use for testing.
However, I don't see it listed on their services & solutions anymore., so
they may not be supporting it. Also the suggestions in my tests were not
all that good on some simple misspellings.
There is one at
http://www.wsdirect.net/ that in the online test produces
better results, but I can' get it to work with VB.Net.
If you sign up as a Google Developer, you can use their web service to spell
check. But it won't handle more than a phrase of about 10 words at a
time--and there is a limit to 1000 such queries a day. It is at
http://www.google.com/apis/.
Do a search, perhaps you can find a free spell checking webservice.