Win7 (64) software RAID 1 VERSES Intel ICHxR RAID 1 resource consumption

I'm hoping someone will respond who has had a lot of direct experience with Windows software RAID 1.

For the last 6 years, I've been a happy RAID 1 camper using my Intel motherboard's builtin ICH RAID controller; which worked quite well.  I didn't even notice when the disks were synching back.

However, recently I switched to two 4TB HDD's.  Unfortunately,  my current embedded controller can only RAID disks which have a a maximum capacity of 2TBs; luckily, that size limit doesnt apply to non-RAID disks.

My question is if there's actually a noticeable CPU/memory hit when using software RAID during heavy reading/writing; such as when recording multiple TV channels at the same time AND/OR when the disks are synching.  I never noticed any significant resource utilization hit when using my ICH controller under any circumstance.

My next question... is there are  dual HDD enclosure under $200 that offers a great builtin RAID 1 capable controller that's compatible with 4TB HDDs?  Using a RAID controller PCI card is out of the question since I'm all out of PCI slots.

Well... it looks like I may have to.  My ICH8R controller can RAID disks up to 2TBs; so, my 4TB disks are out of the question.  At least it can still use them as single disks.  It looks like it would be ideal to RAID1 the two 4TB HDDs via software.  I'm just not thrilled about there being no notifications on RAID status in the Windows system tray.

I am hoping that Windows RAID 1 synching wont be resource intensive; or take longer than ICHxR to complete.