Speeding up inserts

[Matik]

Hello everybody,

Just short question:
I have tables, which are only log tables (very less used for selects),
but there is a lotof writing.
I would like to have as much speed as possible by writing data into
this tables.

create table [tbl] (
[IDX] [numeric](18, 0) IDENTITY (1, 1) NOT NULL ,
[Time_Stamp] [datetime] NOT NULL ,
[Source] [varchar] (64) COLLATE Latin1_General_CI_AS NULL ,
[Type] [varchar] (16) COLLATE Latin1_General_CI_AS NULL ,
[MsgText] [varchar] (512) COLLATE Latin1_General_CI_AS NULL ,
CONSTRAINT [tbl] PRIMARY KEY NONCLUSTERED
(
[IDX]
) ON [PRIMARY]
) ON [PRIMARY]
GO
Question:
Is it better for inserts,, to remove PK but leave identity insert?
How to make this table optimized for writing?
If I will set fill level of the table with 0%, will I winn much?

Once information: this table will be deleted with old data, depending
on row count (oldest ID's will be deleted each night).

Thank You in advance

Mateusz