Issue with creating partitioned tables

I'm doing work with table partitioning to improve performance and have run into different results with 2 different approaches, and wanted to see if anyone else has run into the same situation.

The issue is that when partitioning a new table, SQL forces me to include the partitioning column (a date column) in the Primary Key constraint (previously the PK was an Identity INT column). However, when I implemented partitioning on an existing table with the same structure by creating the clustered index on the new partition scheme, the server allowed me to do it. And when I checked the tables using the $partition function after loading data in them, they looked identical (i.e. both tables had identicial data in the correct partitions).

My questions are:
* Will the server’s behavior when loading to and reading from these 2 tables differ, because the primary key constraint on the 2nd (pre-existing) table is missing the partition column?

* Is the server allowing me to do something with method 2 that it really shouldn’t, or is the error with method 1 not legitimate.

* Also – I'm testing with SQL 2005 - does the same condition exist in SQL 2008 (that’s my next testing step).

Here’s the specific code:

-- Method 1
-- Create the Partition objects
CREATE PARTITION FUNCTION Table1_Submit_Date_PF (DATETIME)
AS RANGE RIGHT FOR VALUES (
'20080101 00:00:00.000',
'20081001 00:00:00.000',
'20081101 00:00:00.000',
'20081201 00:00:00.000'
)
GO

CREATE PARTITION SCHEME Table1_Submit_Date_PS AS
PARTITION Table1_Submit_Date_PF
ALL TO ([PRIMARY])
GO

-- Create the Table
CREATE TABLE Table1 (
Row_Key INT IDENTITY (1, 1) NOT NULL,
Account_Number VARCHAR (24),
Submit_Date DATETIME,
CONSTRAINT PK_Table1 PRIMARY KEY NONCLUSTERED (Row_Key)
) ON Table1_Submit_Date_PS (Submit_Date)
GO

-- Resulting error:
Msg 1908, Level 16, State 1, Line 1
Column 'Submit_Date' is partitioning column of the index 'PK_Table1'. Partition columns for a unique index must be a subset of the index key.

After researching, I found that the PK needed to include Submit_Date (which I can do, but will then have to modify tables with Foreign Keys to this table). So I tried the alternative approach first of creating the partition structure by placing the clustered index for the table on the partition scheme (since that’s what I’ll end up doing anyway):

-- Method 2
-- Create the table with single key PK
CREATE TABLE Table2 (
Row_Key INT IDENTITY (1, 1) NOT NULL,
Account_Number VARCHAR (24),
Submit_Date DATETIME,
CONSTRAINT PK_Table1 PRIMARY KEY NONCLUSTERED (Row_Key)
) ON [PRIMARY]
GO

-- Create the partitions
CREATE PARTITION FUNCTION Table2_Submit_Date_PF (DATETIME)
AS RANGE RIGHT FOR VALUES (
'20080101 00:00:00.000',
'20081001 00:00:00.000',
'20081101 00:00:00.000',
'20081201 00:00:00.000'
)
GO

CREATE PARTITION SCHEME Table2_Submit_Date_PS AS
PARTITION Table1_Submit_Date_PF
ALL TO ([PRIMARY])
GO

-- Partition the table by creating the clustered index on the partition
CREATE CLUSTERED INDEX cdxTable2_SubmitDate
ON Table2 (Submit_Date DESC)
ON Table2_Submit_Date_PS(Submit_Date)
GO

The server allowed me to do this. And after loading data into both tables (Table2 already had data) and checking with the $partition function. They looked identical.