I use an old Seagate Barracuda. So far I've never needed anything else, but FSX is a special case to me. It's 500GB 7200 RPM Sata that came in a 2006 Gateway desktop. I've read that now people are using SSD, and for mechanical HDD that I even need a separate one for FSX. Is this true or will my old HDD do the job? Thanks AVSIM.

The only thing a SSD will do for FSX is improve initial loading times. You *might* get some faster loading textures.... maybe

For FSX, I use an old 200GB 7200 RPM Western Digital that I've also had since 2006. It does the job just fine. The OS and other programs are on the main drive, though. The rationale for keeping FSX and the add-ons on their own drive is that by not interspersing system files, other programs, and so on among FSX files, the hard drive is able to find what it needs faster while flying, which in turn helps read times and performance.I'd recommend at least getting one more hard drive. One like yours goes for $50 regularly on Newegg, and sometimes less. If you choose to spring for an SSD, you'd be much better off putting the OS on it than FSX, because as ryanbatcund suggested, the performance gains for FSX are there but not terribly exciting. By all accounts, however, it'll blow you away when used for the OS.