It depends on how large the ssd is. A dvd is 4.7Gb, so your ssd will need to be at least this size. If it is a commercially produced disc it will be copy protected, so you won't be able to just copy n paste the folders onto the ssd, it will need to be decrypted first using dvd decrypter.
Try here for more info on this, look at the ripping section.
Thanks Pug, wasn't sure if it was as easy as that.
I use 8Gb SSD cards all the time. Perhaps I should have just tried it first myself.
I'm considering getting one of the small notebook sized ultra portable laptops (probably Dell mini 9) with SSDs and no attached other drives. Just thought if I had one and decided I'd like to watch a DVD, I could use a memory stick instead of attaching a USB DVD device.