Intersting comment regarding the scanning.
2010 uses the same engine and the same definitions as 2009, some modules must have been altered if people are finding a difference in scanning speed.
I haven't upgraded yet, Kaspersky are similar to MS, its always best to await SP1!
- sorry edit, forgot to add
Its worth noting that Kaspersky provide absolutely no support for windows 7 currently, they mark 2010 as currently in compatible with any version of windows7, although many users will be able to use it without issue. Might just be worth noting for those who install the RC and then wonder why their AV refuses to install. They have said they will support windows7 when it is released.