If you intend to take up photography as a full time profession, I would be very tempted to get the full version of PhotoShop at the student price, although I understand there may be restrictions on its use for commercial uses. However, as a member of the full price paying public, I would (and did) go for the latest version of Elements which will give you most of the useful bits that the full suite does but for a lot less money!
Nod's law (VERY similar to Murphy's and Sod's) meant that soon after I had bought it, my old computer crapped out and the new one came with some software preloaded; including Elements 7. The one thing I really missed in older versions of Elements was a decent B&W converter - PSE7 (and I assume later) does have a reasonable one, allowing fine tuning of the colour balance much like the channel mixer in CS.
I've played with other PP software but keep coming back to Adobe's products - after all, the current term for photo editting is PhotoShopping rather than PaintShopProing or Gimping.