twaddle
Ah ha, I set the buffers up from 256 to 512 and that seems to have done the trick.
 
Thanks for your help Mesh and Guitarhacker
 
Steve

You're most welcome!! Glad to see it working out.

For a few more dollars you should have purchased the 6i6. It has 3x the features for only a little more cash. In my store here in Canada this was $230.  
See if you can return it and upgrade. It has the SPDIF and comes with the Mix contol software. It is also powered properly with a wall wart. A friend bought the 2i2 and had noise issues. If you look this up you will find it is common with Buss Powered interfaces. The hum is due to USB grounding issues. 
 
http://www.gearslutz.com/board/reviews/906141-focusrite-scarlett-6i6.html
 
 
 

twaddle
He also said that no one buys internal cards these days as they are outdated and have been superseded by the firewire and usb cards that run much better at zero latency. Is this true or just sales talk ?

No one buys internal cards these days, because no one makes an affordable one.
Very high end units are still based on internal cards.
With current machines, USB is pretty close, but I think "much better" is a bit of a stretch.
That said, I am pleased with the performance of my USB interface (Akai EIEpro).
 
Like you, it was a sad day when I had to retire my trusty 0404PCI.
Patchmix threw a few people for a loop, but once you figured that out, it was a rock solid performer.
If E-MU was still a contender, I would mount one of their internal cards in a heartbeat when I eventually get a new PC.
 

Cactus Music
For a few more dollars you should have purchased the 6i6. It has 3x the features for only a little more cash. In my store here in Canada this was $230.  
See if you can return it and upgrade. It has the SPDIF and comes with the Mix contol software. It is also powered properly with a wall wart. A friend bought the 2i2 and had noise issues. If you look this up you will find it is common with Buss Powered interfaces. The hum is due to USB grounding issues. 
 
http://www.gearslutz.com/board/reviews/906141-focusrite-scarlett-6i6.html
 
 
 

 
It's tempting and I might still change my mind but it's a bit more than a few dollars more here.
I paid £139 here and the cheapest I can see it is £199 so that's an extra £60 for an spdif socket and so far using
the standard guitar jack from my pod X3 and if the sound quality is reduced my ears aren't hearing it.
I know the 6i6 has lots of other features but I think I can get by without them.
 
As for the humming there is a very (and I mean very) slight hum now but it's almost gone after upping the buffers in sonar. The guy who runs PMT in Bristol (where I bought the Safire) is an old friend of mine but I doubt he could do me a deal on it as they have to sell everything at on line prices to stay in business and he'd never speak to me again if I told him I was going to return it and buy one on ebay because if I were going to upgrade the the 6i6 I think I'd probably look round for a second hand one.
 
Steve