Before undertaking any of the tweaks in this guide, it's important that your system is up to date and optimized. The biggest gains come from having a fast, stable machine with the latest drivers and the best settings. A lot of problems which you may experience with UT2003 (and other games) will also be solved by doing the following.
Note: The following system optimization information and links may be out of date. For the latest version of this information see my System Optimization Guide which is always kept up to date.
I highly recommend that if you run Windows XP (Home or Pro), without further ado you jump over to my comprehensive WinXP Tweak Guide and follow it from start to finish. Windows 98/ME users should hit Google and hunt around as unfortunately I don't have a specific guide to refer you to. There are many, many Win98/ME guides around, so take your pick.
Make sure you have the right BIOS settings. The most reliable BIOS guide available is Rojak Pot's Definitive BIOS Guide. Note that you can download the whole guide in PDF format if needed. If in doubt, don't mess around with the BIOS, as a bad setting there will cause a lot of grief. Set everything to their defaults unless you know better.
The latest device drivers are very important. In particular I'm referring to graphics card, motherboard, and sound card drivers, as well as the latest DirectX. I provide links to commonly used hardware below, but if I haven't covered your specific configuration, in the first instance check your manufacturer's website, and if you have no joy there, try Google.
The good folks at Epic/DE have given you a head start with regards to drivers. Pop disk 3 of UT2003 into your CDROM drive and you'll find they've included DirectX8.1 (only necessary for non-WinXP users), and under the D:\Extras\Drivers directory of the CD, the latest Official nVidia Detonators for GeForce cards and recent ATi Catalyst drivers for Radeon cards.
To obtain the very latest graphics card drivers, check the following driver download pages for nVidia and ATi. I strongly recommend the latest drivers, even if you have an older card, because these drivers usually have bug fixes and stability and compatibility improvements if not a performance boost also. The game designers agree with me by saying that you should "...ensure that you are running the latest drivers for your graphics card as Unreal Tournament 2003 stresses the hardware and drivers to a greater extent than most available games and we rely on a number of bug fixes hardware vendors incorporated into their latest drivers." Note however that the 40.41 Detonators are problematic with UT2003. Either use the 30.82 provided on UT2003 disc 3, or better yet try the new 40.72 official drivers. For ATi cards, the designers recommend the 7.76 drivers (Catalyst 2.3) and newer because of specific bug fixes for UT2003.
To obtain the latest drivers for your motherboard, for Intel-based chipset motherboards check the Intel Support Site. For VIA-based chipset motherboards check the VIA Support Site. The VIA 4-in-1s in particular can be a bit confusing, so check our handy VIA Driver Guide/FAQ for all your VIA needs. For nVidia-based chipset motherboards (the nForce), refer to the nVidia drivers page link provided above. Also, make sure to check your motherboard manufacturer's website for any recent BIOS updates and install them as instructed. These may help a great deal, especially if you have an older motherboard with newer components or vice versa.
For sound card drivers, once again the latest is always the best, if only because you can be assured that you have the latest bug fixes and game compatibility incorporated into the drivers. For Creative SoundBlaster sound cards (including the Audigy), check the SoundBlaster Support Site. If you run an Audigy in particular, the game designers highly recommend that you upgrade to the recently released Audigy drivers to get "acceptable 3D sound performance". Apparently older drivers will cause problems. For Turtle Beach sound cards, check the Turtle Beach Support Site.
Updating other device drivers, such as optical mouse drivers and the like is recommended, but if you're running WinXP you'll find there is basic support for most any current peripheral.
Overclocking is of critical relevance to UT2003. If your system is overclocked, even by a small amount, then please be aware that UT2003 (just like the original UT) is very sensitive to it. If you're experiencing bluescreens (BSODs), crashes to desktop, sudden reboots or frozen screens, then I guarantee that in the majority of cases it is due to a system component being overclocked too far. Even if your system is rock steady in every other game/application, UT2003 puts a lot of pressure on the system and this will eventually show in the form of a crash. The solution is to reduce your overclock, or even go back to default. As painful as this might be, it will resolve many problems. A PC which crashes during the middle of a game is a lot more annoying than one running slightly slower than you'd like.
Ok, that's the basics. Thanks for bearing with me so far, but it's important to note that if you've followed the above advice, then you are likely to have a problem-free experience with UT2003 as well as most every other game. Now it's time to get down to some UT2003-specific tweaking.