want to get macbook air - but slower than my macbook?

Hi there
I'm looking to get a 'work' laptop. I presently use a standard MacBook, 250 GB, 2.26 GHz which doubles up for home and work.
I thought I'd go for a MacBook air - lighter, sleeker, etc - but to my surprise I find that they not only come with a lot less hard drive, but even have slower (am I right here?) processors than the MacBook that I have...
Just curious if I've misinterpreted something. I'm pretty happy with my MacBook and don't mind getting another one of the same, I was just tempted by the lower weight and longer battery life possibilities.
Is it perhaps possible (or worthwhile) to customise a MacBook air to have more HD space?

ps: My usage is mostly web browsing, uploads with FTP, a lot of word processing and using multiple programs (simple things like Word, Excel, Rapidweaver, Spotify, and many different browser windows) all at the same time.

Thanks for your help / advice in advance!

You'll get a range of personal opinions, links to benchmark tests posted online, and critical analysis of machine on-paper specifications. All I can offer is my actual personal experience having recently switched from a MBP to a MBA...

I went from a 2010 15" MacBook Pro 2.4Ghz i5, 8GB RAM and 128GB SSD to a new "customized" 2010 13" MacBook Air with upgraded 2.13Ghz, upgraded 4GB RAM and upgraded 256GB SSD. After one month with the Air, I have no regrets. It's faster in than my MBP was in performing the casual tasks that you list. The battery lasts longer than my MBP ever lasted. It's much lighter to carry about and it boots up much faster. It comes out of sleep much more quickly as well. Based on these observations, I'm fairly confident you would find it to be as good as, if not significantly quicker than your current notebook. Good luck and enjoy!

When you buy a MacBook Air, what you bought is what you have to live with as there are no upgrades. If you intend to buy one, buy it with the largest flash drive offered and the most memory.

As for speed, the Air makes up for the slower processor with its super fast flash drive (not an SSD, but flash). Read this excellent review done by MacWorld Magazine. LINK

I have the base model MBA, the 11" with the slowest CPU 1.40ghz and it's plenty fast for most things. It'll play 720p videos no problem, it plays HalfLife 2 and Starcraft 2 without any slow down (not at max setting obviously). I love my Macbook Air, I use it for days on end while traveling and never wish that I had my more powerful MacBook Pro. The only reason I keep my Macbook Pro is because of the bigger screen and backlit keyboard.

The thing you gotta remember about the Macbook Air is that it's all solid state so anything involving load times and hard drive reading is super fast. The thing turns on in like 10 seconds, can unrar 40 files in a flash and video converting is pretty zippy. On my Pro I can convert a 30 minute video in just about 2 minutes while my Air takes just about 3... keep in mind the Air is 1.4ghz and my Pro is an i5 2.4ghz.

I have the baseline 11 inch air and the thing flys. I have no regrets. IM pretty sure i will be selling off my macbook pro. Its senseless to have 2 and the 11 inch air does what i want it to. Not to mention the 11 inch air is completely silent no matter what i do to it.

A Macbook Air is not what I'd call a "work" notebook compared to any other Macbook. It's main draw is ultra-portability, which I suppose is ideal for some kinds of work. But if you're talking hard drive space, the need to read and write CD's and DVD's, and other things I consider to be work essentials, a Macbook, or better yet a Macbook Pro is the way to go.

The "Air" is making a big hit with business folks who do a lot of moving around. It's fast, light, and can do most everything that a larger notebook can do. Put it in your briefcase and go. The no optical drive may be a disadvantage to some folks but there's always thumb drives which are getting cheaper and larger in capacity every year.