Canalphones are definitely the way to go, but the notebook isn't good enough of a source IMO. Of course, that will depend on what audio is in it, but a PCDP or mp3 player will still be better. I'd say a 20 gig iPod using wav lossless, or Rio Karma using flacs (I think the Karma can play them) will be your best bet as a source, as will a good PCDP if CD is your most commonly used format.
As far as the phones go, The Etymotic Research ER-4P or 4S with an amp are good choices, Westone UM2 is another, and Stax SR-001 Mk II could be your best bet. The Stax don't isolate, which you really don't need as a library is a quiet enough place already, and they give you by far the best sound quality for the buck in the realm of canalphones. They don't leak a whole lot of sound, and they won't disturb anyone unless they're a foot or so away from your ears. Lastly, the Stax system comes with an amp already, so you won't need to buy that particular piece of equipment, which can easily be the most costly component of the setup. You will, however, need to buy an interconnect between the Stax amp and your source, which won't be very expensive, but should be of high quality, as the 001 is a very demanding system. An AC adapter, and a step-down transformer for Japanese voltage systems is also a good option, as in a library AC power should be easy to come by. With all these add-ons, a good source and IC, the 001 will be a mighty fine sounding system.
If you want an inexpensive but good setup, you can either get canalphones like Etymotic Research ER-6/ER-6i, Shure e3c, and Future Sonics IE3, or you can use Koss KSC-35/75 clip-ons and a small, portable amp, like a cheap CMOY or something of that nature. These cheap little Koss phones sound downright fantastic when amped.
There are a lot of choices. Here are my recommendations, in summary:
Best sound quality: PCDP/good mp3 + good IC + Stax SR-001 Mk II ($400-700).
Best portability: iPod Mini/Zen Micro/Rio Karma + Etymotic Research ER-4P/Westone UM2/Shure e5c ($500-650).
Good budget setup: PCDP + cheap CMOY/small portable amp + Koss KSC-35/75, or mp3/PCDP + Ety ER-6i/Shure e3c/FS IE3 ($220-300).
You could, I suppose, go with a good canalphone and a serious portable amp, like the SR-71, but the Stax 001 will give you better sound quality at a lower price, and unless you really need the isolation, it's not really worth it IMO.