You may read about glowing benchmarks for the newest SSD's.
The sequential benchmarks drive the SSD to it's maximum with programs that issue I/O operations
at a much faster rate than an application can, and does so at high queue levels. 6gb sata looks great.
But, a normal desktop user rarely does anything remotely like that.
The second type of benchmark measures maximum IOPS which will be done at high queue levels again. Think >30.
That is also not what we do. The OS does mostly small random I/O, and at smallish queue lengths.
It is the response time that matters most.
It turns out that at low queue lengths, Most SSD's have the same response time, and they are very low.
That is exactly what you want from a SSD, particularly for the OS.
So, what does this mean when buying a SSD?
Get the capacity you need at the lowest cost per gb
In the past, I had an Intel X25-M 80gb drive. It worked well.
Needing more space, I added another in raid-0 to get a single 160gb image. That worked well too, and sequentlal measurements were impressive.
But, in actuality, I felt no detectable performance change.
Later, I replaced the two 80gb drives with a single X25-M 160gb drive, and saw equal performance, perhaps even a bit faster.
My recommendation is to just get the single 250gb drive, and forget about the baggage with raid-0.
This one says intel review but there are benchies with the other SSD drives (although an older review, still good for a base point).
I highly reccomend not RAID'ing SSD drives. They are plenty fast enough already alone. Yes it is true TRIM is disabled on RAID'ded SSDs - I believe Intel is the only one currently with a firmware update that allows TRIM on RAID (not sure which one though, 1 or 0).
Unless you are doing some massive HD decoding/encoding - RAID 0 won't do much.
I would definately go with the 256GB version. Less hassle, and you have a 2x less chance of 1 of the RAID 0 drives failing.