The primary advantage of an SSD over an HDD is that the access time ( http://en.wikipedia.org/wiki/Disk_drive_performance_cha... ) is somewhere between much, much faster and negligible. So the most common real-world read and write patterns, which are random, will run much faster than with any HDD. The next advantages are faster sustained serial throughput, less heat, lower power usage, and higher profit margins for the manufacturer.
The main effect of an SSD on a home rig will be in improved boot times and program loading times. The SSD will load levels / maps of your games faster, but will not increase frame rates.
The problems that cause your computer to lock up are almost always due to something other than a hard drive speed issue.
7200 RPM is "good;" it is fairly standard. I ran a 15,000 RPM VelociRaptor as my system drive, to reduce response time, until I got an SSD. The SSD blows the VelociRaptor away.