If you're buying a budget laptop, then you probably won't be so interested in running heavy duty games or high-end graphics applications. Hence, the best processor for a budget laptop can usually be any one of the following:

• Intel Core 2 Duo P7350
• Intel Core 2 Duo T5800 and lower
• Intel Core 2 Duo T7300 and lower
• Intel Core 2 Duo T8200 and lower
• Intel Pentium Dual-Core T3200 and lower
• AMD Athlon X2 QL-60 and higher
• AMD Athlon 64 X2 TK-57 and higher
• AMD Turion 64 X2 RM-70
• AMD Turion 64 X2 TL-56 and higher

A picture of two AMD Turion 64 processors
 

If mobility and portability is important to you, then you'll very likely want to sacrifice some peripherals and power for a laptop that's easy to carry around. In that case, the best processor for your ultraportable laptop could be any one of the following:

• AMD Turion 64 X2 TL-66 and lower
• Intel Core 2 Duo L7500 and higher
• Intel Core 2 Duo U7500 and higher
• Intel Core 2 Duo SL9300 and SL9400
• Intel Core 2 Duo SP9300 and SP9400
• Intel Core 2 Duo SU9300 and SU9400

An Intel laptop processor
 

Ok, netbooks happen to be some of the most portable computing devices out there and they're selling like hotcakes. They tend to use very little power but have limited performance. If these netbooks are your cup of tea, then the best processors for your laptop are likely to be:

• Intel Atom N270 and higher
• Intel Atom Z500 and higher
• Intel Celeron M 900MHz Ultra Low Voltage
• VIA C7-M
• VIA Nano L2100 and higher
• VIA Nano U2300 and higher

The extremely small Intel Atom processor
 

If you're into thin and light laptops, which are essentially a class of laptops between ultraportables and desktop replacements, then you might want to consider the following best processors for your laptop:

• AMD Turion 64 X2 TL-60 and higher
• AMD Turion X2 Ultra ZM-80 and higher
• Intel Core 2 Duo P8400 and higher
• Intel Core 2 Duo T7500 and higher
• Intel Core 2 Duo T8200 and higher
• Intel Core 2 Duo T9200 and higher

Desktop replacements are heavy laptops which have a lot of power, similar to desktop PC setups. If you're in the desktop replacement category, here are the best processors for laptop:

• AMD Turion X2 Ultra ZM-80 and higher
• Intel Core 2 Duo T5800 and higher
• Intel Core 2 Duo T7500 and higher
• Intel Core 2 Duo T8300 and higher
• Intel Core 2 Duo T9400 and higher
• Intel Core 2 Quad Q9100
• Intel Core 2 Extreme QX9300
• Intel Core 2 Extreme X7800 or X7900
• Intel Core 2 Extreme X9000 and higher