Ok.. here we go..

The Nikon D40 is a very nice "intro" DSLR. The thing you "lose" by buying the D40 (or D60) is the fact that you cannot use any older lenses. The D40 doesn't have an internal screw drive motor for powering lenses... so you are forced to use the newer lenses that have a motor built into them. This means that you will never be able to upgrade to the better lenses (and you lose out on a huge used market - I buy all my lenses used from other professional photographers). Other than that.. it is a very nice camera.

The kit... well... I always avoid kits because the lenses they include are typically inferior to what you will really want later on. Having said that... you'll probably be fine with what is included. If you are coming for a P&S world, you'll notice some difference. However, once you get a hold of a pro lens.. you'll never want to go back. Keep in mind the price difference though... the pro 17-55 lens I use on my camera cost me more than the price of the whole kit..... USED! I paid around $950 for the lens.. it retails for over $1200 new. So, it is all a matter of how much you can afford.

The flash is awesome... it is basically the top of the line Nikon flash and I use this on my camera. The model that is one step down is also great (and about $100 cheaper) but doesn't allow you to remotely control other flashes... if this isn't important to you, I'd be the SB-600 and save some $$$... I use my SB-800 to remotely trigger and talk with other SB-800 flashes and other strobes for a studio setup... much improved over the built in flash.

Just so you know... I highly recommend the now discontinued D50 over the D40... you can find a lightly used D50 in the used market for around $375... couple that with the 18-70 F3.5 for $200 used and you have yourself an awesome setup... or you could buy the 18-200 VR for around $600 used and for the price of your kit.. you'd have a complete 1 lense setup that is better quality glass than the kit lenses..

As for memory cards, you'll need SD cards for the D40 - you'll definitely want to get a high speed card... you'll notice the difference if you shoot RAW with the camera and take 3-4 photos in a row. I like Kingston and Sandisk.. buy them (and other things) at newegg.com and read the reviews. I buy all my PC equip from newegg... they are the best online company out there. I'd recommend buying a card reader from them too.. can be found for only $15 or less and it is so much easier than using the camera and USB cable.. you also save your camera battery that way too.

Polarizers/UV protector will depend on the size of the lenses... you can find out the info online and then you'll want to get a good one - the quality of these vary greatly from the lowly Quanteray from Ritz camera to the awesome B&H... prices vary accordingly of course... welcome to an expensive hobby.

Good Luck... and as always.. let me know if I can answer any other questions (or spend your money for you!)..