More memory is also helpful, but your real problem is disk.
1. Transaction log on dedicated RAID1 (or RAID10)
2. Data on RAID10
3. Tempdb on dedicated RAID1
Use perfmon to monitor for disk bottlenecks, make appropriate config changes.
Use SQL profiler to monitor reads/writes/duration into a table 24/7 . Analyze it. Since it is third party, you can only make improvent with index maintenance, possibly dropping/adding indexes.