I'm playing the Nov '09 England in South Africa ODI series in ICC 09 (as England). I'm having a pretty easy time of it surprisingly. I'm not taking many wickets, but I have kept them (I keep losing tosses) to a sub-250 score once - using maximum bowling aggression throughout.
The main thing that has let me off the hook is that, no matter how aggressive I bat them, Strauss and Pietersen just don't get out. I'm used to struggling a lot more than this in 50-over, but that may be because I'm more used to playing domestic, and there the batting can be more brittle.