Sorry about that, whenever I get a hardware question i always get the devices confused. in short, the card is an Nvidia GeForce GTX 2xx series, and the radeon is of the 5xxx HD series. I can tell you that for sure.
Right, but like said definitely need more precise card names

A GTX275 would blow a HD 5450 out of the water for example, but if we're talking about a HD 5870 then that's an entirely different story.
EDIT: ok just saw your last post
I cannot tell you my specs off the top of my head, but I do know I am running off an ASUS essentio CG-1330-07 series at the moment, also I am having a bit of trouble posing fast enough...
That system has indeed a HD 5450, which is crap. So yeah if it's a GTX 275 or such it would definitely be an upgrade.