I have a computer that is connected to the living room TV (a Panasonic) via HDMI. There is no other monitor connected. My problem is that the computer, which is running Windows XP, does not allow me to set the proper resolution for the TV. Both the graphics adapter and the TV should support the 1280x720 resolution, but it cannot be selected - the only available options are 1280x600 and 800x600, both in the "native" Windows dialog box and the custom Intel graphics options dialog box. Do anyone have a suggestion for a solution for this? Things I've thought of:

• Setting the resolution directly in the registry (where?)
• Installing some "custom" monitor driver (the TV manufacturer does not appear to provide any, currently the "generic" one is used)

Details on the setup:

Connection: DVI output on the computer via a passive DVI->HDMI adapter to the HDMI input on the TV, audio is run on a separate link, the TV is able to combine video and audio without any problem, the problem is there regardless of whether or not the audio is connected. The connection is several meters long through some walls, for this reason using a VGA cable instead is not an option.

Note that the report explicitly says that the TV supports 1280x720. Still, I am not allowed to select it in Graphics Options, only 1280x600 and 800x600 is available. For 800x600, there's a lot of black around the edges; for 1280x600, the screen is "zoomed" so the edges of the monitor image (like the taskbar) is not visible.

Other: The computer is running Windows XP. More recent versions of Windows are not an option (I have no licence). Linux is probably not an option (some of the video streaming sites I plan to use do not support it, I think)

I wrote the rest of the details below. Thanks for any help!!

TV: Panasonic TX-L32X10Y, European version; a 720p 32" quite "regular" LCD TV. 

Allowed resolutions according to manual:

Signal name: 640x480 @60HZ Horizontal frequency: 31.47 kHz Vertical frequency: 60Hz
Signal name: 750/720) /60p Horizontal frequency: 45.00 kHz Vertical frequency: 60Hz
Signal name: 1,125 (1,080) / 60p Horizontal frequency: 67.50 kHz Vertical frequency: 60Hz

(this is exactly how the manual presents it. PC via D-SUB (VGA cable) and "regular" HDMI 
have more alternatives.) Messing with the "zoom" settings on the TV does not affect the 
available resolution options on the computer.

Computer: The following is a printout from one of the graphics adapter option pages. 
I think it covers most of it. The computer is a Dell.

        INTEL(R) EXTREME GRAPHICS 2 REPORT


Report Date:            04/17/2011
Report Time[hr:mm:ss]:  20:18:02
Driver Version:         6.14.10.4396
Operating System:               Windows XP* Professional, Service Pack 3 (5.1.2600)
Default Language:               English
DirectX* Version:               9.0
Physical Memory:                1021 MB
Minimum Graphics Memory:        1 MB
Maximum Graphics Memory:        96 MB
Graphics Memory in Use: 6 MB
Processor:              x86
Processor Speed:                2593 MHZ
Vendor ID:              8086
Device ID:              2572
Device Revision:                02


*   Accelerator Information   *

Accelerator in Use:             Intel(R) 82865G Graphics Controller
Video BIOS:             2972
Current Graphics Mode:  1280 by 600 True Color (60 Hz)



*   Devices Connected to the Graphics Accelerator   *


Active Digital Displays: 1


*   Digital Display   *

Monitor Name:           Plug and Play Monitor
Display Type:           Digital
Gamma Value:            2.20
DDC2 Protocol:          Supported
Maximum Image Size:     Horizontal: Not Available
                        Vertical:   Not Available
Monitor Supported Modes:
1280 by 720 (50 Hz)
1280 by 720 (60 Hz)
Display Power Management Support:
        Standby Mode:   Not Supported
        Suspend Mode:   Not Supported
        Active Off Mode: Not Supported

(disclaimer: this question was also asked at the Wikipedia Reference Desk some time ago and might show up in a Google search. I got no useful answers there.)