How much memory can my SharePoint web front-end (WFE) servers use? It's a common question, and this post is an attempt to answer it for common scenarios. Briefly: 4 GB is the maximum recommended for most scenarios, though you may be able to use more if you're hosting other applications on the same server, including other web applications.
This is to explain what the ULS logs are, why they exist, and how to read and write 'em. In a nutshell, the Unified Logging Service (ULS) writes WSS 3.0 and MOSS events to SharePoint’s Trace Logs, and these are stored in the file system in ...\12\LOGS. Collectively this location and its files are commonly referred to as the “ULS Logs” though MSDN calls them the Trace Logs.