Purchasing laptop for mixing etc., vst, creative E-MU?

[dubcomesaveme]

Hello, I currently own just a desktop, and am purchasing a laptop very soon.

Some important stuff I want to be able to do is use it for mixing. Right now I use mainly Sony Acid, Ableton Live, and VST plugins. I assume regardless of software used what will be important is having lots of RAM and a pretty powerful dual core for running multiple audio apps with minimal latency.

I want to use an AKAI MPD32 drum controller with it MPD32 MIDI/USB software control surface , aka I want to be able to perform\loop stuff live as an instrument rather than just composing and rendering.

Customizing and ordering a Dell XPS M1530
The Dell Online Store: Build Your System

The audio options are integrated "hd audio", a "software upgrade" to some creative audigy type deal, and ExpressCard SoundBlaster X-Fi Extreme sound expansion card.

Are any of these upgrades worth it? The software upgrade sounds like they just give you drivers, I could probably just install kX drivers if I wanted that type of sound improvement. Also, an X-Fi expansion card? Should I just save money for something like the Creative E-MU?

Speaking of the Creative E-MU, does anyone have any opinions on it? I guess its main claim is you get to use its hardware effects with no cpu load in all of your software via VST... does this make it worth the money? Will latency be super low with Core 2 Duo Processor T8300 (2.4GHz/800Mhz FSB, 3MB Cache) and 4GB DDR2 RAM with stacks of software VST plugins? Perhaps the X-FI expansion card is decent just for sound quality improvement over internal, and get some type of external breakout box later if I need it?

I don't think I will be doing much in the way of recording from external sources, mainly mixing\performing\outputting. If I do any recording would prob only be one voice\instrument at a time. I'm guessing at this point E-MU is prob overkill?

Also, I have a 250GB USB western digital external that I would prefer to store all my samples\music on for mixing as it can be connected to either desktop or laptop. Does this add latency? Like if I want to perform something live on AKAI MPD32 interface can I have everything stored on external and no problems\lag\stutters cus it loads into RAM? Do I need to bother having a decent size\speed internal laptop hard drive? (preferably not, would rather rely on external)

If anyone has any thoughts let me know, or suggestions for other web resources I should explore\post on instead.

Thanks