Latest intel® microprocessors are quite different in design and performance than their predecessors. Performance wise they are much better than the older Core 2 series. Due to differences in design they are not compatible with existing motherboards. Unlike earlier Core 2 series, intel confuses their customers with its branding strategy. E.g. earlier Core i7 processors have four separate cores and latest one has (Core i7 985) six separate cores, with no relationship to number seven.
Latest processors are
1. Core i3
2. Core i5
a. Series 600
b. Series 700
3. Core i7
a. Series 800
b. Series 900
4. Core i7 extreme
a. 985
b. 975
c. 965
Performance is higher