Consider Linux, either commercial or free. Bundled software Often MS Office, whether you want it or not. Video card Compatibility. May be a bottleneck if slow. 3-D acceleration important for some applications, including some games.
Quality is important.
Minimum resolution 1024x768. Look for Energy Star compliance and power management. Hard disk EIDE interface is common. SCSI is faster but a lot more expensive. CD-ROM drive Speed at least 8x, usually 40x or more.