Hi Guys
Im trying to decide which arduino to get, and cash is not a problem.
I would classify myself as a beginner but a good programmer. Should i get the Arduino Duemilanove or the Arduino Mega.
Which would be easier to start with or are they basically the same just with better features?
Any advice will be great
P.S
(my current project is a remote control paintball gun, using 3 servos)
Unless you have an identifiable need for the extra resources of a Mega, get the Duemilanove. Not only is it cheaper, if you fry the processor which isn't difficult to achieve, its easily replaced just by removing and replacing a socketed chip. Replacing the processor on a Mega is a non starter unless you have the gear and talent to deal with soldered surface mount chips.
Im trying to decide which arduino to get, and cash is not a problem.
That's a nice problem not to have. 
I would classify myself as a beginner but a good programmer. Should i get the Arduino Duemilanove or the Arduino Mega.
I think in time you will find that you will want to obtain several different boards in different form factors and features. So a cute answer would be to get them all. Most recommend getting the standard current mega328 board as a starting point, but again the mega board is not that much more costly and sure has a lot more memory size, I/O pins, extra timers, 4 serial ports, more user interrupt pins, etc. I really like my Seeeduino mega board 
Which would be easier to start with or are they basically the same just with better features?
They are equally easy to use, just more features and resources on the mega. A lot depends on the type of applications you envision playing with. If it involves a ton on I/O pins then the mega makes for a cleaner project that might not require external shields for things like shift registers to expand I/O pin. But of course some have asked about how to control 300 servos on an Arduino, so some applications are challenging no matter which board you have. ;D
P.S
(my current project is a remote control paintball gun, using 3 servos)
Just about any Arduino (or Arduino clone) could handle that as the I/O doesn't seem too high a count, nor is the program size very demanding. More thought will have to go into how to power three servos and the board and what kind of wireless method you will need.
Lefty
Thanks for the advice. I like the idea of the Duemilanove, because of the fact you can remove the controlling chip and replace it. Could you also use the Duemilanove to programme the chip and use it as a stand alone microcontroller. The chip is cheap, so this might work well.
Any thoughts, or is there an easier way to replace the arduino with a stand alone microcontroller.
The thought being that once i have built my prototype i would like to have my arduino back.
Do a search on "standalone arduino", there are many ways of doing it, my particular favourite is using strip-board.
Heres a thread that covers many possibilities, including my strip-board job. http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1259185696
Could you also use the Duemilanove to programme the chip and use it as a stand alone microcontroller.
Yes, you can do this, as pluggy noted, but with one caveat:
You don't want to do it too many times.
What I mean by that is you don't want to get in a situation where every time you need to program a chip, you remove the one from the Duemilanove, put yours in, program it, then swap again. The reason why is that the IC socket on the Duemilanove is not designed for repeated insertions and extractions of that nature (the occasional insertion/extraction for replacement purposes is OK); eventually the socket will wear out and/or have intermittent contact on some of the pins. There is also the real issue of possibly bending pins on the ATMega...
For that kind of prototyping, what you will want to set up is a 28-pin ZIF (zero-insertion force) socket, either on a shield or as a standalone unit, just for programming. Using that kind of a socket, you can repeatedly program chips all day long and not worry about it.
Alternatively, you could skip the bootloader and get an ISP programmer (or use the Arduino itself), and then on your standalone Arduino setup add headers for the ISP connector so you can program it in-circuit.