First of all, you need to find out which hard drive interface your laptop has.
If it's old enough to have IDE, in my opinion it's not worth it to spend money on an SSD. IDE SSDs are rare and just as expensive, plus you won't be able to reuse one when you buy a new laptop.
If it's SATA, I personally recommend Kingston HyperX 3K. I have been running one for 4 months in my desktop machine. It works perfect and it's much faster than the OCZ Agility I also tried.