Two Databases vs Single Database

I searched Google a lot over this topic but was not satisfied with answers I got,
I am having a website and I want that users from that website should be able to log into wordpress as well,
For this purpose having one database would be a better idea or having two seperate database is a good idea, my original database is going more than 52 MB , with 2000 users,
But I fear if I make separate database I wouldn't be able to integrate website with blog in future,

See original post by Waqar Akram