Dell Vostro 1500 Motherboard Swap

I bought my vostro 1500 new from dell in 2007, although i have several faster core i series computers, i still use my vostro 1500 every single day and with the SSD it is faster than most of the machines i have, plus it boots extremely quickly. Original battery still lasts 3-4 hrs. 

Only real issue is the 2.6GHZ core 2 duo is starting to show its age a bit. I love the design of the laptop, its very solid and reliable but im wondering if anyone knows if there is a faster processor than the 2.6 core 2 duo for it? Every source online tells me that the 2.6 is the max for it. Its not slow by any means, but when running multiple tasks sometime it will near 100% cpu usage. It has 4gb of ram and never uses more than around 1.5 or 2 of it so i know this isn't a problem. Is there any other motherboard that is slightly newer that will fit in the vostro 1500 case? 

Out of all the laptops ive ever had the vostro 1500 layout is hands down the best, probably better than my $1700 SAGER and if there is any way i could fit a better motherboard in there i will do it. Plus the thing is very solid, does not look old at all and it never overheats.