Generally the 2x7200 drives will be faster than the single 10k, unless they are in a RAID 0 (read speed they might still be faster but write it will be like 1 7200 drive)
no here is an fanboy oportunity as its finest. Best thing to do is a bit of research in this area, http://www.pcbuyersguide.com/hardware/storage/hd_reliability_report.html
is an example of things to read
Seagate are very reliable, but i have never had many problems with any WB, or maxtor
The spin rate isnt all that governs the speed of a hard drive, things like burst rate also affect it. A well desgined and manufactured drive which is tuned to perform faster rather than last that 2 years longer than everyone elses would be western digital drives. If you want a bit more reliabilty but reduced speed then go for the gd 'ol seagate.
Granted you will never notice this peed difference unless you really push your HDD to the max, you may see a slight difference in transfer rates when burning to CD's ect...