CS5 should cover anything you need and for a 199.00 bucks you can't go wrong. I had to pay 579.00 for CS4 and then upgrade to CS5 for 169.00 
The best thing about CS5 is all the new features, plus Bridge and ACR are all included as part of the complete program. Nothing else to buy, unless you want some add-on's like Topaz Labs or Imagenomic's Portraiture software.
They're add-on's to photoshop you can buy separately and use directly inside of CS5.
CS5 is a complete package and LR is a solo image library that allows you to edit too. I like Bridge because it's simple and you open into ACR straight from the files you select in Bridge, then they open into CS5 for the final output.
CS5 is much more than image editing software and the extended version also has 3D software. CS5 will allow you to create your own images from scratch. It's a graphics interface. You can add anything you can imagine to your photo's.
CS5 allows you to make composite images from two, three, ECT. photo's. You can change the backgrounds, add layer masks, and anything from anywhere. If you have a photo of a boat and a lake, but wanted to add something to the image. CS5 will do it. LR will only allow you to perform image editing related to color, exposure, WB and so on. CS5 is a true image editor with all the same capability's of LR and beyond.