Mainstream support for Access 2003 is guaranteed for almost another three
years ...

http://support.microsoft.com/lifecycle/?p1=2509

... so even if support for ADPs was dropped in the next version - which I
think is extremely unlikely ... you can go right on working with ADPs in
Access 2003 at least until the end of 2008.

I'm not saying you should choose ADPs, just that you should decide on the
basis of current technical merit rather than on speculation about what may
or may not happen in the future.

I've heard that MS Access team itself recommend use *.mdb/*.mde as SQL
Server2005 FE, instead of *.ADP. The fact is SQL Server 2005 was realeased
almost three years later that Access2003. ADP, as a FE specifically designed
for SQL Server, did not know all those new features/objects in SQL Server,
so, you can not use it as you do with SQL Server2000 (you still can connect
to it, as you already know, but you cannot create SQL Server2005 object,
like table, view, sp. Facing such hurdles, ADP is literally useless). When
SQL Server2000 was released (also after Access 2000, the first version
sopprting ADP), MS quickly released Access SQL Server2000 compatibility
service pack. But this time, the Access team even not recommeds to use ADP
for SQL Server. At least it indicates ADP's future is not clear at this
point. SO, for SQL Server2000/7, yes, APD is OK (even for upcoming Access12,
I'd bet it would be OK, MS is fairly good on supporting what is already
there), but, for SQL Server2005 or later, no, I'd not invest into it until
its future is cleared up. With Access12 coming out very soon, still not a
single word is heard on whether ADP will support SQL Server2005, that is not
a good hint to me.

Actually, my knowing on this info, is mostly from this NG and somewhere on
MS site (cannot remember the links). If you search this NG, you may find a
bit more info on this.