Btw, I was mixed up on the 64 bit compatibility by the cnet review. You should check it out and see what performance difference 64 bit makes(not alot). Also, another issue is driver compatibility. Users must get a 64 bit driver for all their hardware. Alot of hasstle involved, when there is very little benefit.
Also, look here. Longhorn in 32 and 64 bit editions.
Finally, if the laptop can run the programs you want it to run, 64 bit compatibility will not be an issue. Software developers will not alienate a huge portion of the market who do not have 64 bit processors. In most likelyhood, 32 bit applications will get support well into 2008, 2009. By that time, your laptop will be 4 years old, and a new upgrade will be in store. Even if you get a 64 bit laptop, it will probabably also be lagging in performance and require an upgrade. So 64 bit compatability is almost a non-issue.