Which is where your problems creep in I'm afraid, so, what you need to do is make sure you have the graphics set to the lowest possible settings, and make sure you have the game set to run at the native resolution of your monitor rather than it trying to resize it as well.

Ok, you're running Vista, not a favourite OS for gamers, and very hard work for a laptop to run, even with the 4gb ram, thats because you're on a mobile/laptop CPU which will no doubt be running on a lower voltage and not as fast as it's desktop equivalent.

So, to claw back some performance, turn off all the Vista nice things such as Aero. You can also do some research on the net to find other services you can turn off which will claw back some more ram and CPU for you. Turning those off and disabling their start up options will also help it boot quicker as well.

If you're playing it over wireless then you will get bad lag and possibly a framerate drop. Thats because wireless just can't compare to a wired connection for gaming, and if you're in an area where there is signal intererence you'll lose packets. Try testing your connection at speedtest.net, they also run a ping test so you can see how you fare with your net connection on wireless and wired and see the differance.

I do run 2142/FS on my laptop from time to time, it's similar to yours but runs Windows 7 and has dedicated graphics. I still have to turn the eye candy down and get horrific lag a times!

Thats actually a REALLY weird one.  Usually the open maps are fine, and it's busy (Cities + Endor) which cause framerate issues.  This will totally screw up space maps for you, but try turning down view distance, see if anthing improves. 

Whare are your system specs?

@ATM8M: as twigs says, please specify what you mean by lag.  Latency to servers, or low frame rate?  The causes and fixes for both of the problems are different.

I'd always suggest making sure your graphics drivers are up to date to start with.

Other than that, not much else I can suggest without more info ATM, such as what hardware you are running.

Have either of you tried overclocking your graphics? Not something I should really suggest, but you can get programs that allow you to manually change graphic settings to try and get a bit more performance from your card.

Unfortunately FS is a little bit more graphics intensive than BF2142.  I believe it was reported a few years ago that First Strike on low is roughtly equivilant to Regular BF2142 on Medium.

What I can suggest is sticking to the low denisty maps such as Battle Of Taloraan, Strike At Parmel, Imperial Convoy Raid, Lok Wastelands, Battle Of Ryloth(Maybe), Jundland Wastes (maybe) and Rhen Var Research Facility.

What I find curious is that your computer can handle the forest maps.  Although the trees are pretty rough, especially on low settings, there are bloody loads of them, so I find it strange that your computer can handle those without much of a hitch.  What are your computer specs, primarily your CPU Speed, Graphics Card and Operating System.  It's possible your performance could increase with some driver updates.

My Operating system is Vista home premium 32 bit.
Toshiba Manufacturer
Processor: AMD Turion 64 X2 Mobile Technology TL-60 (2 CPUs) ~2.0GHz
1918MB RAM
DirectX 11
Graphics card: ATI Radeon X1200 Dac type: 400MHz Total memory: 829MB
Vertex: 2.0 Shader: 2.0

Maybe You could Point me to some custom maps that I would be able to play?
The only map I can play is the forest map. Not the one with the walker in the preview image, the other forest map. Like clean out of something.
Cause Its not fun with only one map to play.

What I can suggest is sticking to the low denisty maps such as Battle Of Taloraan, Strike At Parmel, Imperial Convoy Raid, Lok Wastelands, Battle Of Ryloth(Maybe), Jundland Wastes (maybe) and Rhen Var Research Facility.

What I find curious is that your computer can handle the forest maps.  Although the trees are pretty rough, especially on low settings, there are bloody loads of them, so I find it strange that your computer can handle those without much of a hitch.  What are your computer specs, primarily your CPU Speed, Graphics Card and Operating System.  It's possible your performance could increase with some driver updates.