In order for you to play Crawl on Windows with minimal graphics settings, your computer must meet the following requirements
OS *:
Windows XP (sp2) or later
Processor (CPU):
1.66 GHz Dual Core Processor or equivalent
Memory (RAM):
2 GB RAM
Graphics Card:
NVIDIA since 2006 (GeForce 8), AMD since 2006 (Radeon HD 2000), Intel since 2012 (HD 4000 / IvyBridge)
DirectX:
Version 9.0c
Storage:
400 MB available space