I'd like to think it will as your increasing the write speed of the primary hard drive.
Laptop HDDs in my experience write between 50 and 80 mb/sec. SSDs seem higher, depending on the model some may be between 80 and 200mb/sec. As far as the chipset (memory, i/o controller and SATA bus among others) is concerned, you might be bottled up else where.
One thing I can definitely say, is you'll notice a big difference in system start up from a cold start. My T400s with an SSD vs HDD is night and day. I'm looking at an SSD for my X120 soon though.
Hope something I said is helpful in some minor way
Someone with more experience will post I'm sure.