Have SSD Issues with Read, Write, Erase and Rewrite Been Fixed

A couple of years ago when I built my last PC I really wanted to use a SSD for my C: drive that only held the OS and Virus SW, everything else goes on to my D: drive (1.5T) and G: drive (WD 2T external back up).  I am now looking at ways to speed up my system w/o having to spend more too many more $'s.  I have a Asus P58/1366/Premium MB, 2.8 cpu, 24GB of Ram and a 10,000 rpm WD Raptor OS drive.  When I was doing my research for the build SSD's weren't able to rewrite and with all the W7 and Norton updates the drive would be filled fairly fast.  Has this changed in the last couple of years, can you now rewrite data instead of taking new space and not being able to reuse old space or are the SSD's still the same in that respect as they were.

I realize that magnetics are the bottleneck for pc speed regardless of how big a buffer the drive has or how much ram your system has.  Has the SSD become the best solution now for OS drives now?

Thanks for your answers.

Phil