Thinking to migrate to Vista X64(64 bit system) from XP 32 bit

[Castout]

Just that will Dangerous waters and Silent Hunter 3 run okay in Vista 64 bit system?

Just how much more secure a 64 bit system when compared to a 32 bit system?
Is Vista more secured than XP?

I use my PC mainly for entertainment, Games and the internet.
And my processor can handle 64 bit OS just fine.

Should I migrate to 64 bit system?

The thing is for using 64 bit Vista the minimum memory is stated as 4 Gigabyte. So that's the minimum. I'm thinking to use either 6Gb or 8Gb RAM. The last time I checked the biggest single RAM available was a 2Gb chip. So I'm going to need at least 3 or 4 of them.

My biggest interest to use the Visa x64 is the relative security of 64 bit system when compared to 32 bit system. Actually I do not need to use multiple application simultaneously as what is offered by Vista x64 OS.

Should I migrate or should I delay?