Is the Nvidia 6500LE enough ?

Oh yeah im running Windows Vista Home Premium 32bit if that makes any difference

well, it sounds like you might need more memory, a better cpu (semprons are single i believe), video card, and depending on what you get, you might need a new PSU.

though, we would need more info, you havent really posted that much
also, how much are you willing to spend?

oh, and the 6500LE is old, it was pretty crappy when it came out, so no, it will no be enough

Actually if ALL you want to play is lotro than you cpu is more than enough for that game...it doesn't require much power at all...get 2gbs of ram and a CHEAP! video card....maybe a new psu...

Be careful if you update your processor that the Dell BIOS supports it.

+1 EXT64.
Also you need a low profile card and, according to the Dell documentation, one with a very low power draw:

http://support.dell.com/support/edocs/systems/dimc521/e...

Best performance within the power limits given by Dell is the HD4650 ans the Egg does have low profile versions on sale.

I have the exact same Dell c521, the onboard graphics is actually a 6150LE which is even worse than the 6500LE. Your computer supports socket AM2 CPUs guartanteed up to the Athlon 5600+ X2. However some people have successfully upgraded their Dell's to a "Birsbane" version of the 6000+ Athlon X2 CPU. You want to make sure you haver the latest 1.1.11 BIOS, the older may not recognize the CPU. One thing to note is that when I installed my Athlon 5200+, it showed up .1-.2GHz different probably because of the BIOS.

Your standard Dell PSU has 280W and 16A on the 12V rail. I'm currently running a 8400GS which is not a gaming card unfortunately. BUt some people have also successfully ran a low profile 9600GT in this system. The card might get a bit toasty in their though, the C521 airflow isn't very good.

You can upgrade the RAM to PC-6400 800Mhz which is the maximum type of RAM thats supported, you can also run them in dual channel. I currently use the Crucial Rendition 1GB DDR2 800Mhz RAM which is really cheap for the performance. I'm planning to run them in dual channel once I get the other one  

Low Profile Cards for Dell C521

SAPPHIRE 100253HDMI Radeon HD 4650 512MB Low Profile - http://www.newegg.com/Product/Product.aspx?Item=N82E168...

ASUS EAH4550/DI/512MD3 LP Radeon HD 4550
Free Alone in the Dark game w/ purchase - http://www.newegg.com/Product/Product.aspx?Item=N82E168...

SPARKLE SX96GT512D3L-NM GeForce 9600 GT 512MB (These specs of the low profile 9600GT are very close to those of the low profile 9800GT) - http://www.newegg.com/Product/Product.aspx?Item=N82E168...

SPARKLE SFPX95GT512U2L GeForce 9500 GT 512MB - http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Good luck to ya!