I am also a teenager at the age of 17 but I have been using computers more specifically fsx for some time now... since fs2000 was released when I was 9, but fsx is a massive leap forward in graphics but unfortunatly computers have to do the same to keep up with it.
Your graphics card is a very good graphics card for its time a few years ago... but considering the latest graphics card is a 9800gt2 and would bring your frame rates to about 30 with all sliders up at max in fsx (which is average and playable (below 15 frame rates per second and it is very dodgy) You can find out your frame rates by halding down "shift" and pressing the "z" key three times would bring up some figures up the top; your frame rates is listed and a number folled by "fps" e.g. my'n is "30fps". post what your frames rates are and what setting you are using on fsx for that.
bearing all that in mind I had made an unfortunate discovery a year ago which said that and HP Pavilion Desktop computers use a unique motherboard layout on the inside which might mean you will be unable to upgrade your computer... therefore I decided not to go for a HP and to build my own computer. I am running a
quad core q6600 processor
windows vista 32bit
3gb ram
8800gtx video card
asus sli prenium nvidia motherboard
580W Power supply
1x 320gb HD & 1x 80gb raptor HD
and I get 20fps with sliders to max in innsbruck (austria mountains on fsx)
I think the only options you have is to go to nvidia website and download the latest drivers for a 6150 SE graphics card click the following link to get your latest drivers which I found for you; (you will need to restart computer after installation)
http://www.nvidia.com/Download/Scan.aspx?lang=en-us, or you can get in touch with HP and see if you can get a new graphics card from there... if not then I am sorry to inform you but you would simply have to by a whole new PC ):
Hope that helps