Upgrade suggestion

Im looking to upgrade my computer and would like some oppinions and suggestions.
Is it even worth upgrading ? Am I better off to just let that PC to other family members for web browsing and such?

My current computer specs are:
asus formula motherboard
intel q6600
2GB DDR2
geforce 8800GTS 512
2x seagate 512GB in raid 0

Im looking up to something like:
Gigabyte GA-Z77X-D3H
Core i5-3570K
8GB DDR3
OCZ Vertex 4, 256GB
GPU: should i buy cheap one for old computer and use 8800GTS512 in new build or its not worth it.

Im looking for stable system and not going to overclock, want as much performance as I can get and I dont want to spend fortune.

any and all suggestions are welcome.
Thanks.