An SSD will Speed up:
.. Loading the operating system. You can Power on and from the Time Of "loading operating system to opening a program is about 15 -> 20 sec. Benifit - depends on how often you boot/reboot system and How "Ticked-off" waiting for the computer to complete power on cycle.
.. Program loads are almost instantsanous. I click on a link to a speadsheet and both the Program (excell) is loaded and the spreadsheet is there befor I can drag a Mouse to edit a fiel.
What a SSD will not do:
.. Speed up/improve watching a dvd or Blu-ray
.. Speed up downloads, or surfing the web, or downloading email.
.. Will not speed up loading files that are not on the SSD. ie Loading a LARGE spreed sheet - Very fast if ON SSD, but if file is on HDD then slowwww.
In a Nutshell, a SSD will speed up reading what is already on the SSD and writing data that is already in memory to the SSD.
Personnally Love my SSDs have 7 installed in 4 systems. Have not had one problem ( Includes older SSDs from SATA II versions. I do stay away from OCZ and Sandforce 22xx SSDs. Perfer Intel, M4, and samsung 830 for reliability.
The Intel sata II SSD and the Samsung 430 (also) a Sata II are probably the highest rated SSDs in terms of reliability, AND there is not a big performance diff between them and a SATA III SSD (benchmarks - Yes, Real life as stated, not a big diff).
Bottom line - go for it.