Expensive yes – underpowered arguable.

It is true that Tablets (and also many notebooks) have lower speced processors. However the processor is only part of the picture, and in Windows XP is often not the bottleneck that results in poor performance.

The other factors to consider are the amount of RAM and the speed of the hard drive in RPMs. These other two often make a bigger difference to overall performance then getting the next fastest processor. Many tablets are available with optional RAM and disk upgrades for a marginal cost.

Also if you identify a Laptop and a tablet that both meet your technical requirements and then divide the difference by how long you expect it to last. I did a hypothetical example on my blog (http://www.pringle.net.nz/blog/PermaLink,guid,b5ebc770-748e-418d-b8f2-7afa2f0cbfab.aspx) and found that the difference was $6.80/wk.

Once you have that number you can work out if the extra flexibility will provide at leaast that much benefit. If it does – buy the tablet.