My Laptop speed reduced drastically, how to improve it?

I have sony vaio with core i7, 4gb ram 2gb graphics with dual boot windows (win 7& win8). Since last month or two, the booting speed of win 7 has hampered drastically. it takes about 10 minutes to work smoothly. while start up it shows intel rapid storage technology not running for a while. What should I do to improve it? win 8 works perfectly. Please help!!!!!!