Guyton and Hall is definitely a solid textbook. However, I think you'll find that reading textbooks is a pretty extreme waste of time for most classes. Textbooks tend to include far more information than you're responsible for, and you don't have time to be learning extraneous details. I know many people in my class were "textbook learners" before med school, and I currently know a grand total of zero people who regularly study from textbooks. They're references for concepts you need a bit of fleshing out on but nothing more. I stronglyadvise not buying textbooks, but if you really feel like you have to have them, at least buy them used. You'll be really pissed you wasted your money if you don't. I can't emphasize this point enough.
Okay, with that little disclaimer-ish junk out of the way, here are the texts we were "required" to buy:
Intro to Clinical Medicine:
Textbook of Physical Diagnosis - Swartz: Useless. You'll never touch it.
Phys:
Medical Phys - Guyton and Hall: I hear it's a good book for reference, but it's too detailed and has too much information. Costanzo's book is far better, and her Board Review Series (BRS) book is better still.
Respiratory Phys - West: Nobody I know even owns this. Don't bother.
Musculoskeletal Medicine - Bernstein: Ditto.
Microanatomy:
Langman's Medical Embryology - Sadler: This is quite literally the only textbook I actually own. Sometimes it is phenomenally useful (for cardio) and sometimes it mercilessly drowns you in useless minutiae (for GI). It's cheap, so I recommend it.
Rapid Review Histo and Cell Bio - Burns and Cave: Solid gold. It's very, very useful for both cell bio and micro, but it's a little light on the pictures. Hopefully you'll have lecture slides to supplement it.
Color Texbook of Histology - Gartner and Hiatt: I hear it's not so good. Burns and Cave has everything you need anyway.
Cell Bio:
The Cell - Cooper: Fairly worthless, but it's a decent reference. Again, Burns and Cave has you covered, but this one wouldn't be so terrible to own if you just MUST have it for whatever reason.
Biochem:
Textbook of Biochem with Clinical Correlations - Devlin: Dear God, do not throw away your loan money on this useless piece of crap. It's incomprehensible and hopelessly detailed. Buy Lippincott's, and forget everything else exists.
Gross:
Clinically Oriented Anatomy - Moore: Pretty useful, actually. It has a ton of detail, but the clinical correlations are quite nice. It's not a necessary purchase, but I'd suggest getting it just for completeness.
Grant's Atlas of Anatomy - Tank: I don't like it at all. Netter's is far better, in my opinion. Still, it's an atlas, and it will work.
Grant's Dissector - Tank: Amazing. The dissector is absolutely indispensible. It'll hammer home relationships like nothing else will. Absolutely buy this. The pictures are pretty poor, so you may need your atlas (or a corpse) around to make things clearer.
Books I've used:
BRS Gross - Chung: I don't like it. The pictures are really terrible, and it puts me to sleep every time I try to read it. It also has way more information than you'll probably need. The clinical correlations are nice, though. If you can find a cheap, used copy, pick it up. Otherwise, you should be okay without it.
BRS Phys - Costanzo: It's pretty dry reading, but that's the case with all of this high-yield stuff. However, the information is exactly what you'll need for class. I can't speak for the shelf exam, but this baby has seen me through thick and thin so far. A great buy.
High Yield Embryology - Dudek: Useful, but there isn't much to it. I hate embryology with a passion, so anything that can give me the take-home points in a nutshell is welcome. I recommend it.
Atlas of Human Anatomy - Netter (a.k.a. "Netter's"): It's really very good. I don't use it all that often, but when I do, it's excellent. It's the best of the illustrated atlases, no question.
Color Atlas of Anatomy - Rohen: This is far and away my favorite purchase. It contains photographs of immaculately dissected cadavers and is extremely useful for studying for practicals. Definitely buy it.
Lippincott's Illustrated Reviews: Biochemistry - some guy: Another med school essential. I'm willing to bet most of your classes' slides will be taken directly from this book. The information is concise, but it's actually a decent read. Worth every penny.