Until recently, for most people, this question would have required little thought. The high cost of SSD Drives (Solid State hard Drives) coupled with the modest capacities of the drives available on the market, meant that few people would have considered them. The lighting fast access speed and good shock resistance may have tempted a few people to part with their hard earned cash. Most of us would have drawn a sharp intake of breath when we saw the price and immediately started looking for a cheap hard drive to fulfil our computer data storage needs.
Well, the good news is that the prices have been dropping. I don't see 2009 as the the year when SSD sales overtake HDD sales, because the prices are still too high for mainstream PC use. However, I'm convinced that will happen within the next year or two. Historically, we've seen spectacular improvements served up by the HDD manufacturers, but HDD development is probably near its plateau and will not show the same rate of improvement as we have seen in the past years.
By comparison, it is only recently that SSD development has been taken up seriously and we can look forward to massive improvements in the years to come. Although the large SSD's are still prohibitively expensive, we now have SSD's with a capacity large enough to rival the biggest HDD's.
For smaller sizes of drive, the big advantage which SDD drives have (better shock resistance and faster access speed), make them a viable alternative for use when building a computer for your car.