I've got vista installed and it works flawlessly.
A few things you need to do:
∙Turn off UAC. This allows EVERY program to be run with administrator priveleges.
∙Make sure the install and patch loaded properly.
∙Video drivers. they have to be UP TO DATE with vista. I have a problem about once a month where the game crashes because my drivers are OOD. Not sure why it does that, but as soon as I update them, perfecto.
∙My old PC was a 2.3 ghz P4 with 1 gig of ram. I had ALL kinds of problems with BF2, even with my trusty x1950 pro on point. Lag, insufficient ram problems, extremely long load times, etc. That was with XP. Vista is a resource HOG. If you can afford to, double your RAM and upgrade your processor.

Heres something helpful from the BF2 Tweak Guide:

Windows Vista Users: If you're having problems running this game under Windows Vista, first make sure that you're using the latest Vista graphics and audio drivers for your hardware, and the latest version of this game (see page 4 for patch details). Next, make sure you don't change your UAC settings after the game has been installed, as due to Virtualization this can change the location of the game files and settings. If you can't launch the game successfully when UAC is enabled, you will need to run the game with full Admin privileges. To do this either right-click on the launch icon and select 'Run as Administrator', or right-click on the launch icon, select Properties and under the Compatibility tab tick 'Run this program as an administrator' then click OK. I strongly recommend that you refer to the TweakGuides Tweaking Companion for Windows Vista for more information - in particular check the 'Gaming in Vista' section of the Graphics & Interface chapter; the UAC section of the PC Security chapter; and the 'Personal Folders' and 'Directory Junctions & Symbolic Links' sections of the Windows Explorer chapter. These will tell you how you can fix game-related issues and also explain the relevant differences of Vista.

Launching/Loading Issues: The most common problem with BF2 is that the game crashes to desktop or goes to a black screen when you first launch it. The reason for this is either incompatible hardware (make sure you meet all the minimum specs), or more usually the fact that you're not running at the default Windows XP refresh rate (60Hz). By default the game tries to launch at 800x600@60Hz initially, so your system must be able to run that same resolution and refresh rate, otherwise the game will abort. If you are using any refresh rate override program/method, disable it (e.g. if you're using Refresh Force, click the 'Restore Original Settings' button and apply). Alternatively, see the Advanced Tweaking section of the guide for details on how to set a different startup resolution, in case your graphics card/monitor simply cannot do 800x600@60Hz resolution. Once you've got the game running, you can then change the resolution to suit your taste in the in-game settings, and importantly you can select a higher refresh rate. Then you can reapply any refresh rate override and the game will launch without any problems. To set a non-standard resolution see the Advanced Tweaking section.

The tweak guide can be found HERE
Hope that helps.