Use a SSD as your boot drive for your OS. You don't need such a big drive. Windows 7 and up adjust to take advantage of SSDs (TRIM etc). Just get a lightning fast one.
Stick in a couple of big HDDs for data.
One of my workstations is configured like that. Nice and nippy.
Been watching the 512GB SSD kits fall in price for my laptops. Quite tempted by the Samsung kit that includes Norton Ghost and cables so you can easily backup and restore your existing HDD.
Comparison boot speeds really show the increase in speed. Here's an example video using the same laptop as I have.