Don’t waste your time here when you could be investigating.
You do not give enough information for me to
really give an educated answer. Plus I’m not well read on the X300.

With the 9600 I’ll guess that it has a 128-bit memory interface.
With the X300 is it 64-bit, or 128-bit memory interface?
And just to make sure are we talking about the X300 and not the X300 SE?
Do you have a link to a Dell PC page for us to look at?
You can over clock (push) the X300 very well also-if you know how.

Even if the X300 is slightly better (?) you still cannot go wrong with
the 9600.
I don’t know what the future holds-only at some point you may even find some money to upgrade as prices drop.
With this in mind you may want to think of the 9800 Pro or XT AGP cards or X600
PCI-E card or…, the cost of these in the future and what they bring.

Oh and you did not miss the insult-Kacperski insulted MOH:PA.
I’m American and I don’t use bucks, so whats your point.
Is the Dell being purchased with currency?

__________________
March or croak, march or croak
All your lives a cosmic joke
Fill your days with piss and smoke
The wolf waits at your door
--Lemmy