I suppose opening a 24" pipline . .
. . from Redmond directly into his bank acount doesn't qualify as a "technical negative", but expect a forced march to Longhorn and Office 11.
An important negative is Microsoft's stated goal of making all .NET systems dependent on Microsoft servers through Internet connections. This opens serious questions about security, reliability, licensing and ownership of data.
Microsoft has had to back off a bit due to a massive display of lack of trust, which forced them to rework and reposition the Hailstorm services (temporarily).
Another negative is being limited to Intel servers running Microsoft operating systems, because the server processes that are the building blocks of .NET business systems run only on those servers.
Microsoft has made lots of noise about .NET being multiplatform, but so far their multiplatform implementation extends only to different versions of Windows. I would expect Windows clients to remain an imperitive. with some very minor "check box" exceptions.
The multilanguage aspect of .NET seems to extend only as far as the ability of other languages to imitate the characteristics of C#. Their native strengths generally are irrelevant to .NET.
You can expect Java to remain excluded or severely crippled in the .NET environment.
All of these are more business negatives than technical negatives, but that's the nature of Microsoft - technology is deployed mainly to lock you into an unequal business relationship.
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