1745 is so much better than the 1737, even though it has less memory...it could just be a windows 7 vs. vista thing, but this is a nice machine.
Sound: 1745's sound is so crisp and you can really feel the subwoofer doin its job...i tried using skype on the 1737 and had so much trouble hearing the other person...on the 1745 that wasnt an issue
Screen: people actually look like people. the 1080p HD screen provides more color ranges and is significantly brighter and better than the 1737.
General Appearence: dell went back to the glossy exterior for the 1745 and i think its a plus. the 1737 ended up with fingerprints all over it that wont come off easily.
1745 is actually a little thinner and lighter than the 1737. also, the touchpad is HUGE meaning it gives you lots of room to play with the different gestures. however, it can get in the way sometimes when your typing...it makes the mouse jump around.
1 bad thing: theres only 2 "dedicated" USB ports (3rd is the esata). this is down from SIX on the e1705...so ill probobly get a usb hub or something to make up for it.
things i wish it had that the 1737 had: bluetooth (dont have any bluetooth stuff yet but wish i could get it) and backlit keyboard.
overall i am very satisfied.