This listing is for a BRAND NEW (all new parts) custom-built DOS/Windows 98 retro gaming PC with the following specs:

-ECS K8M800-M3 Motherboard (Lenovo OEM) w/VIA K8M800 chipset
-Socket 754 AMD Sempron 3300+ at 2.2 GHZ
-512MB DDR 400 ram
-128GB Lexar solid state hard drive
-Avance Logic ALS4000 Sound card w/SoundBlaster & FM Synth Support in DOS mode
-Hardware OPL3 and FM Synth
-15-pin Gameport
-AGP Video - ATI Radeon 9600 Pro w/128MB VRAM (FireGL T2 variant installed as a 9600)
-Compaq 3.5" 1.44MB floppy drive (3.5" drive in a 5.25" enclosure)
-Lite-on CD-rom drive (IDE)
-SD/CF Reader
-VIA Rhine II Fast Ethernet Adapter (10/100)
-7 USB 2.0 ports (3 front, 4 rear)
-Serial Port
-Parallel Port
-PS/2 Keyboard and PS/2 Mouse port
-Antec VSK3000 Case
-350 Watt OEM PowerMan Power Supply
-Dual Boot option at startup for Windows 98SE or DOS

This computer has PS/2 keyboard and mouse ports (green and purple plugs).  A PS/2 keyboard and mouse are REQUIRED (at a bare minimum to install drivers for any USB keyboard and mouse you may intend to use) and are not included.

Every single part in this build, right down to the cables, is brand-new or new-old-stock.

About this build:
New parts for builds such as that are becoming exceeding difficult to source at reasonable prices, but I will continue to offer these builds at these prices for as long as I can.  This is an early 2000s roughly period-correct build with some modern amenities such as a solid state hard drive and a CF/SD reader.  Boot time is lightning fast and this machine runs rock-stable.  I tailored it to be optimally compatible with the vast majority of the Windows 98 game library as well as the latter half of the DOS game library.  There is audio support when booted into DOS thanks to the ALS4000 sound card, which is fully automatically configured when you select DOS from the boot menu.

Video Card:
The FireGL T2-128 is a faster version of the T2-64 thanks to double the vram (128mb instead of 64) and faster clock speeds.  It uses the exact same chip as the Radeon Pro 9600 and as such, runs perfectly fine without any issues with a Radeon 9600 driver, which is how I have it configured.  Benchmarks are great for an AGP card of the era:

3dMark99
11,951 Overall
131 FPS - Race
110 FPS - First Person

3dMark 2000
12,739 Overall
99 FPS - Helicopter - High Detail
89 FPS - Adventure - High Detail

3dMark01
10,085 Overall
65 FPS - Car Chase - High Detail
84 FPS - Dragothic - High Detail
84 FPS - Lobby - High Detail
54 FPS - Nature

Sound Card:
The ALS4000-based sound card gets along nicely with the VIA chipsest onboard this motherboard. This card provides solid audio in Windows 98 and also provides SoundBlaster and FM audio for a number of DOS games when booted into DOS mode.  The one advantage this card has over a Yamaha card is that it doesn't require a memory manager, and thus, games like Tyrian and Jazz Jackrabbit have full audio support.  The one disadvantage is that some (though not many) games hang upon exit, requiring a restart.  It is also a somewhat "noisier" card than other other cards (ie, background hiss), though I have alleviated much of this by muting several things such as the microphone port and also optimizing volume output levels in both Windows and DOS.

Floppy and Optical Drives and SD/CF Reader:
This motherboard has a number of legacy connections including 2 IDE connectors and a Floppy connector.  I included a Compaq-branded 3.5" 1.44 MB floppy drive for those old late-generation DOS or Windows 95 game disks you might have lying around.  I also installed an SD/CF reader, so you have plenty of multimedia options.  The Optical drive is rated at 52x speed and supports CD's only.

Solid State Hard Drive:
Without going into details of the work that went into figuring out how to get this to work, the SSD is a natively SATA drive, is connected directly to one of the motherboard's 2 SATA ports, and is properly detected in the device manager and has its DMA mode enabled.  The CD drive is an IDE drive but also has its DMA mode enabled.  There is an unused SATA port and an unused IDE port on the motherboard, the SATA port of which cannot be used due to Windows freaking out when 2 SATA drives are connected.

DOS Configuration:
Upon powering up the computer, you will be greeted with a menu screen where you can choose to boot into Windows or DOS.  DOS offers you several different configurations including whether to load a mouse driver (CTMOUSE) and a CD drive driver (which will assign the letter D to the CD drive).

I tested a number of games including Doom, Duke Nukem 3d, Commander Keen 4, Police Quest, King's Quest, Realms of Chaos, Jazz Jackrabbit, Tyrian, and Wolfenstein 3D.  All worked perfectly with functioning sound (games without soundblaster support such as Police Quest will send sound to the motherboard's speaker which does work) except that a few games hang upon exiting and require a system restart. Note that Commander Keen 4 may be jerky depending on your monitor - in my testing it plays perfectly smoothly on a Samsung monitor I have but is jerky on a Dell monitor.

Windows Configuration:
Installed on Windows 98SE is TomComm (an unzip utility), Sea Moneky web browser, DirectX 8.1, 3dMark99, 2000, and 2001 benchmarking software, and all hardware drivers.  The Device Manager is 100% clean and has no red X's or exclamation points.