I have heard the 1.6ghz is kinda slow. It will be used just for general use word, quickbooks, multiple monitors, email and web. Will the 2.4GHz new macbook show me a noticeable difference. Will a ram increase on the air make a difference, and is it easy to do on the air?
You honestly won't notice the difference with those programs in speed. And on a laptop you only have one output for the monitor so it will only support one monitor in addition to the internal display. For the RAM, the MacBook Air's RAM cannot be upgraded, but 2GB of RAM should be plenty for your needs.
Trackpad, does the air use all the same multi-touch gestures as the mac book.
It supports all of the multi-touch except for the 4 finger gestures.
Case build, I know the macbook is rock solid in structure how about the air?
I have the MacBook Pro and the MacBook Air, and build quality is similar between them. Both feel very solid.
Monitor port, is there really a difference?
The difference is that the MacBook Air supports displays up to 1920x1200 and the MacBook will support displays up to 2560x1600 but only with the dual-link adapter which is $99. You won't realistically notice the difference unless you plan to buy a 30" display.
What are you going to be using the computer for? If the (very slight) increase in mobility is not absolutely critical, you will very soon become frustrated with the shortcomings of the Air.
Air Vs Macbook:
The only thing the Air has over the Macbook is a better quality screen.
Air is much slower - when stressed, the 1.6 GHz CPU decreases its speed even more to avoid overheating. The Macbook is a constant 2 or 2.4 GHz.
Air has a slow hard drive, the sort used in iPods.
The old Air has a much slower graphics chip than the new Macbook - the Macbook's Geforce 9400M can actually play games! (it has about half the performance of the old Macbook Pro's 8600m GT, so you'll have to dial back the graphics effects but it still goes MUCH better than the old Macbooks or Airs)
The Air has very few ports - not a good desktop replacement!
Cannot easily upgrade RAM, hard drive, or change the battery in the Air. This is easy in the Macbook.
The 13-inch Macbook is still extremely portable - 0.95 inches thick, 4.5 pounds weight. Air is 0.76 inches, 3 pounds.
I can only recommend the Air to you if it will only be used when "on the go". It is NOT suitable when used as your own computer. If you can handle the slight increase in thickness/weight (honestly, it doesn't matter, the normal Macbook is still very thin and light), go for the new Macbook.
In time, you'll only become frustrated by the Air's many shortcomings for only one gain - 0.19 inches and 1.5 pounds. The Air may make you look rich, but it will soon wear off. I once considered getting an Air, and am happy I did not.
Just my $0.02.
Hello, nice to meet you. I'm typing this to you from my MacBook Air right now and I've owned the product for a bit now so I've had plenty of time to compare it with other computers. The MacBook Air's processor is about 1/3 slower than the MacBook's yes, will you notice it in the applications that the OP mentioned, no. The MacBook Air will perform those tasks fine, I even use my MacBook Air with Photoshop CS4 and Lightroom and it performs decently.
I use my MacBook Air to do any editing on the road, while at home I use a MacBook Pro which is faster, but the difference in speed does not blow you away like you would expect from your post. And my MacBook Air has not gone down from 1.6GHz when stressed, it runs at that speed throughout when being stressed (And that's when I'm doing photoshop and lightroom on it, I'd know if it slowed down).
I really don't see where the OP would see the speed boost of a faster hard drive with the applications they listed. And I don't see where the OP mentioned gaming, so there would not be a perceived difference in the graphics power with those applications. The MacBook Air's ports can easily be extended with a USB hub (Which actually makes you quicker on the go since you only have to unplug one USB port and everything is practically setup when you come back). 2GB of RAM will be plenty for the uses the OP has for the computer.
When I got the MacBook Air, I additionally had an iBook G4 12" which is very similar in weight to the MacBook and I noticed a huge difference in the weight. I immediately gravitated towards the MacBook Air because of it, the MacBook Air makes me want to use it everywhere. And you'd be fooling yourself if you think that the MacBook Air is only good for people who are on the go 24/7.
I go to my MacBook Air first when I want to use a computer so it gets more home usage than my MacBook Pro which I now only use for extensive photo editing. And as you said, you're only basing your opinions on observations of the product specs (you said you didn't own the computer) while I'm basing mine on experience with the product

.