SSD prices are down.
You might well replace the two 500gb hard drives with a 1tb ssd.
Do not buy a cheap ssd. Samsung EVO is, today likely the most reliable and best performer.
As to raid, what do you hope to accomplish?
The value of raid-1 and it's variants like raid-5 is that you can recover from a drive failure quickly. It is for servers that can not tolerate any interruption.
Modern hard drives have a advertised mean time to failure on the order of 500,000+ hours. That is something like 50 years. SSD's are similar.
With raid-1 you are protecting yourself from specifically a hard drive failure. Not from other failures such as viruses, operator error,
malware, raid controller failure fire, theft, etc.
For that, you need external backup. If you have external backup, and can tolerate some recovery time, you do not need raid-1
Raid-0 has been over hyped as a performance enhancer.
Sequential benchmarks do look wonderful, but the real world does not seem to deliver the indicated performance benefits for most
desktop users. The reason is, that sequential benchmarks are coded for maximum overlapped I/O rates.
It depends on reading a stripe of data simultaneously from each raid-0 member, and that is rarely what we do.
The OS does mostly small random reads and writes, so raid-0 is of little use there.
In fact, if your block of data were to be spanned on two drives, random times would be greater.
There are some apps that will benefit. They are characterized by reading large files in a sequential overlapped manner.
Here is a older study using ssd devices in raid-0.
http://www.tomshardware.com/reviews/ssd-raid-benchmark,3485.html
Spoiler... no benefit at all.