如何优化忙表的索引？

i have this table of comments (little over 1 milion rows) that gets around 10.000 inserts and around 100.000 queries against it every day, and minor deletions and updates. the query that gets the comments causes performance issues that sometimes it locks up entire database and i am getting a lot of timeouts. please help me adjust my indexes and anything else so that it performs better. below i included the info about it, if you need more please ask. i rebuild all indexes daily and run a sql server 2008 web edition on a 2008 server.i have this table of comments (little over 1 mi