If you’re contemplating adding an ultra-portable laptop to your traveling writer arsenal, a recent set of AT&T ads featuring Bill Kurtis has probably intrigued you. AT&T has a promotion where you can get a mini-netbook for $199 when signing up for a service plan.

You get that final price after rebates and instant savings, but many tech blogs criticize the plan, saying the final cost of the laptop is far more expensive because of the $60-per-month data plan (for 5gb of transfer). When your two year contract is over, you’ll have paid as much for the data plan as you would have for the laptop.

It’s easy for freelancers to get swayed by these arguments, but I always remind my friends that data plans, laptop costs and other expenses can be written off, so that’s a bit of a moot point, at least for me. I know there is calculator voodoo you could do here, but I’ve already moved on, thanks.

What sways me isn’t the “final cost” since I can leverage that cost at tax time–it’s performance.  Mark Spoonauer complains in his blog post about the three-cell battery life of the AT&T discount netbooks, saying we’d be better off with a full-sized model.  He also says at least one of the models on offer here is substandard.  “…the Inspiron Mini 12… is so mediocre, Dell no longer sells it directly.”

That concerns me–I was almost sold on the idea of a mini with an AT&T plan (I already have an iPhone and thought I could cut a deal). But this makes me think twice. Bottom line, read ALL the fine print and do some additional homework on these offers before getting too married to the idea. After all the competition also has a reputation for offering sweet deals. Verizon and Sprint have also run similarly-priced deals this summer.