my first advice would be to go to both the corel and adobe sites and have a serious look at both products, paying special attention to things like working with layers, does it have a 64 bit version, can it work in many different color formats like rgb, cmyk, hsl, and so on. when i bought pse 4 it didnt have nearly the features i was expecting and wasnt nearly as good as the comparable psp product. but, i havent bought a pse product after that so i dont really know what changes adobe has made to that product since i bought 4.
i can tell you that psp x2 is very good for working with photos. i can also tell you that it's much more stable than psp xi was. i dont think i've crashed once with psp x2 running on a 64 bit vista machine. that in itself is almost worth the buy. but, adobe products tend to be quite stable also, so no advantage one over the other there.
the gimp is actually quite remarkable, though i havent played with it for a few years now, i was quite impressed with how many features it actually had back then and i know it's got quite a dedicated group of folks who use it and develop it. and, it's free!
but, there is one advantage elements has over psp or the gimp; it's adobe. and in the world of graphics, adobe is still king with photoshop. so, when you're ready to graduate to photoshop, elements is going to help you probably more with that than psp. myself, i like psp x2, but it would be harder for me to migrate to photoshop than someone who was taught in elements, not impossible, by any means, but just a bit more of a learning curve because of the differences in the two programs.
so, the final evalution has to be yours. i've given you a little bit of data, but you are the one who has to decide. i do believe you could probably download a demo of each with a 30 day run time, so maybe that would be the best way for you to make the comparison and thus the decision