Some laptops have a DVI output jackand there are DVI --> HDMI converters. You might be fortunate enough for that.
Alternatively, you might be able to set the laptop to treat the TV as a 2nd monitor and use whatever input on the TV that is compatible with the laptop's output jack(s). Many laptops can do this and use a different resolution for #2. If your graphic card allows you could set the #2 (TV) resolution to the equivalent of HD ie something like 1080 x 900.
For sound you might have to run an audio cable from the laptop to your TV or sound system's aux jack.