Digital Home Canada has a large article comparing DLP and LCD rear projection HDTV technologies.

The advantages of DLP over LCD include:

• higher contrast ratios
• more Consistent Performance throughout the life of the set
• no screen door effect
• newer models offer greater resolution

The advantages of LCD over DLP include:

• brighter images than DLP for equivalent wattage
• richer more natural colours
• no rainbows
• wider viewing angle

For more, check out the article.

Digital Home Canada - HDTV Insight: DLP or LCD Rear Projection?