Hi,
I just built myself a new machine which has an ASUS motherboard with is UEFI based.
I noticed after I installed Fedora 17 that my sda is MBR and my sdb is GPT:
sda is a ssd drive. Should the ssd drive be GPT or is MBR okay?
sda is 60Gb drive.
MBR is okay.
GPT is needed:
a) when you want a partition to be bigger than 2GB, or when at least one of your partitions has to begin beyond the first 2GB of its disk;
b) when you want the fastest (they say) possible boot using the UEFI firmware bootmanager and UEFI boot partition(s) with UEFI OS loader(s).
However every UEFI based motherboard can boot very well a disk with MBR, too.
So: if it ain't broken, don't fix it. 
Stay with your MBR.
--
Bye
EDIT: I apologize for my typo: of course I meant 2TB, not 2GB. Thanks to fpmurphy for pointing it out.
MBR partitions can be greater than 2Gb. GPT is required when your disk is greater than approx 2Tb and using 512 sector sizes.
Of course, it was a typo: I meant 2TB. 
In MBR every partition is defined by its starting sector and its size in sectors. Both values are limited to 32 bits. So a partition max size, as well as its farthest possible starting point, is:
(2^32-1) x 512 = 2,199,023,255,040 bytes.
This means that you can use a MBR for two 1.5TB partitions in a 3TB disk, for instance. On the same disk you can't use MBR for a single 3TB partition, nor for four 750GB partitions, nor for two partitions of 0.5TB and 2.5TB ...
Today even disks having 4kB sectors show to the system virtual sectors of 512B. So the disk sector real size doesn't affect the 2TB limit.
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Bye