Don't lift for more than an hour, if at all possible, because after about an hour you head into a catabolic state, so you're undoing what you're trying to build. Some people find that taking specific carbs around their strength workouts contributes to better gains and intensity with the lifting (look for TKD in the CKD/Body Opus forum). That's what I do, and it's working nicely for me.

Just make sure your exercise increases are gradual, so that you don't end up injured (it can happen!) or overtrained.

The website stumptuous.com is a great resource, but not Atkins-friendly. For more Atkins-friendly info on weight lifting in particular, this forum and the CKD forum (especially the stickies) are full of great advice.