I am running on an issue using C# SendKeys.Send method. I am trying to replace keyboard keys with other keys, for example when I press \"a\" in keyboard I want that key to b
Another option you have is to use Low-Level keyboard hooks to trap the old character and then send the new one. It will require some P/Invoke, but it gives you the ability to completely trap the original key so apps don't even see it.
SendKeys.SendWait
This may not be what you want/need, but if you just want to remap some keyboard keys, I would suggest looking into using another keyboard layout, or creating a custom layout. You can create new layouts with this:
http://msdn.microsoft.com/en-ca/goglobal/bb964665.aspx