What's on my computer

Hello,
I recently had my computer rebuilt to where it is 99% new. I was told that Windows 7 was installed and the screens and programs are different from my old system ( I had Windows XP ) . Althought everything is much different my screen still shows Windows XP when I start up.
Also my card readers do not work all the time. I've used the CD I received with them and the strat up procedure tells me I don't need to do anything . I got a message saying "new hardware found and ready to use ( Promaster digital multi card reader) .
Any help will be appreciated. Thanks

Pat L