Installing oracle RAC 10.2.0.1 install and patch to 10.2.0.5 directly or install CRS ASM and RDBMS then patch? I'm installing my first RAC and I was wondering if I should install CRS 10.2.0.1 (we are still at 10g for compatibility reasons) then patch to 10.2.0.5 before I install ASM (then patch) and finally rdbms (then patch)

or if I should install CRS / ASM / RDBMS 10.2.0.1 and then patch to 10.2.0.5 in the same order.
I would go "CRS / ASM / RDBMS 10.2.0.1 and then patch to 10.2.0.5 in the same order" just to be sure I follow the most typical way that others went before 10.2.0.5 became available. But it's just me, your first proposition will work as well.

Both alternatives guarantee that at all times:

CRS version &gt;= DB version
CRS version &gt;= ASM version