If you go the name brands (Toshiba, ASUS, HP, Compaq) you always pay $$$'s. If you are on a budget then have a look at Dell. They offer a Intel i5 2.53 Ghz Processor, 4G DDR3 RAM, 500GB 7200RPM HDD, ATI 1GB Graphics Card all for $1100. This all should be enough for Planetary imaging.
I would also like to hear why HDD drive speed is an important factor..I know it may provide faster down load but I wouldn't think that much faster than 5400 RPM. If you said 10 000 RPM then yes..but that would be an over kill.
I have just received my Flea3...now you have me wondering
And I thought finding a suitable Filter Wheel to fit this rather small camera (fits between two fingers) was my only problem.