A. This is as much a "religious" debate as a technical one. Both products are good (as are others such as DB/2, Informix, Sybase...). My advice would be to stick with whatever you have the technical skills/experience with, and don't change for the sake of it. SQL Server, Oracle and DB/2 will all be around for a long time - and most of the other dbms's should be too.
But for those who have to have a pro and con list, here is one to get you started (though no doubt some/all of the points would be contested). It assumes SQL 7 and Oracle 8.
Pro's of SQL Server
On the *same* hardware running NT - SQL Server has the best tpcc numbers. (www.tpc.org). Oracle has higher tpcc numbers but only on non-NT platforms - and the cost per tpcc is higher.
Mobile/client version of product is exactly the same as the server one (with Oracle it isn't)
SQL 7 is generally accepted as easier to install, use and manage
SQL Server is cheaper to buy than Oracle (though this is such a small part of lifetime support costs it really shouldn't be a consideration)
Extra facilities "in the box" - e.g. OLAP, English Query, DTS
Pro's of Oracle
Scales higher than SQL 7 - whether your system needs to scale that high is a question you need to ask yourself (if you need ultimate performance you should be looking at DB/2 on a cluster of IBM 10-way mainframes). SQL 7 should be fine for 1 Terabyte of data and 2500 users. (These are conservative figures and are more to do with NT's scalability than SQL's).
Clusters better than SQL
More powerful 3GL language than SQL - PLSQL vs TSQL
Runs on non-NT platforms - e.g. Unix, MVS.
Been around longer.
More fine-tuning to the config can be done via start-up parameters.